diff --git a/internal/diff/procedure.go b/internal/diff/procedure.go
index cde3b0d5..47115cf7 100644
--- a/internal/diff/procedure.go
+++ b/internal/diff/procedure.go
@@ -40,10 +40,10 @@ func generateModifyProceduresSQL(diffs []*procedureDiff, targetSchema string, co
 		procedureName := qualifyEntityName(diff.Old.Schema, diff.Old.Name, targetSchema)
 		var dropSQL string
 
-		// For DROP statements, we need just the parameter types, not names
-		paramTypes := extractParameterTypes(diff.Old)
-		if paramTypes != "" {
-			dropSQL = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s(%s);", procedureName, paramTypes)
+		// For DROP statements, we need the full parameter signature including modes and names
+		paramSignature := formatProcedureParametersForDrop(diff.Old)
+		if paramSignature != "" {
+			dropSQL = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s(%s);", procedureName, paramSignature)
 		} else {
 			dropSQL = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s();", procedureName)
 		}
@@ -88,11 +88,11 @@ func generateDropProceduresSQL(procedures []*ir.Procedure, targetSchema string,
 		procedureName := qualifyEntityName(procedure.Schema, procedure.Name, targetSchema)
 		var sql string
 
-		// For DROP statements, we need just the parameter types, not names
-		// Extract types from the arguments/signature
-		paramTypes := extractParameterTypes(procedure)
-		if paramTypes != "" {
-			sql = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s(%s);", procedureName, paramTypes)
+		// For DROP statements, we need the full parameter signature including modes and names
+		// Extract the complete signature from the procedure
+		paramSignature := formatProcedureParametersForDrop(procedure)
+		if paramSignature != "" {
+			sql = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s(%s);", procedureName, paramSignature)
 		} else {
 			sql = fmt.Sprintf("DROP PROCEDURE IF EXISTS %s();", procedureName)
 		}
@@ -110,6 +110,29 @@ func generateDropProceduresSQL(procedures []*ir.Procedure, targetSchema string,
 	}
 }
 
+// formatParameterString formats a single parameter with mode, name, type, and optional default value
+// includeDefault controls whether DEFAULT clauses are included in the output
+func formatParameterString(param *ir.Parameter, includeDefault bool) string {
+	var part string
+	// Always include mode for clarity (IN is default but we make it explicit)
+	if param.Mode != "" {
+		part = param.Mode + " "
+	} else {
+		part = "IN "
+	}
+	// Add parameter name and type
+	if param.Name != "" {
+		part += param.Name + " " + param.DataType
+	} else {
+		part += param.DataType
+	}
+	// Add DEFAULT value if present and requested
+	if includeDefault && param.DefaultValue != nil {
+		part += " DEFAULT " + *param.DefaultValue
+	}
+	return part
+}
+
 // generateProcedureSQL generates CREATE OR REPLACE PROCEDURE SQL for a procedure
 func generateProcedureSQL(procedure *ir.Procedure, targetSchema string) string {
 	var stmt strings.Builder
@@ -118,8 +141,21 @@ func generateProcedureSQL(procedure *ir.Procedure, targetSchema string) string {
 	procedureName := qualifyEntityName(procedure.Schema, procedure.Name, targetSchema)
 	stmt.WriteString(fmt.Sprintf("CREATE OR REPLACE PROCEDURE %s", procedureName))
 
-	// Add parameters using detailed signature if available
-	if procedure.Signature != "" {
+	// Add parameters - prefer structured Parameters array, then signature, then arguments
+	if len(procedure.Parameters) > 0 {
+		// Build parameter list from structured Parameters array
+		// Always include mode explicitly (matching pg_dump behavior)
+		var paramParts []string
+		for _, param := range procedure.Parameters {
+			paramParts = append(paramParts, formatParameterString(param, true))
+		}
+		if len(paramParts) > 0 {
+			stmt.WriteString(fmt.Sprintf("(\n    %s\n)", strings.Join(paramParts, ",\n    ")))
+		} else {
+			stmt.WriteString("()")
+		}
+	} else if procedure.Signature != "" {
+		// Use detailed signature if available
 		stmt.WriteString(fmt.Sprintf("(\n    %s\n)", strings.ReplaceAll(procedure.Signature, ", ", ",\n    ")))
 	} else if procedure.Arguments != "" {
 		// Format Arguments field with newlines if it contains multiple parameters
@@ -223,55 +259,54 @@ func proceduresEqual(old, new *ir.Procedure) bool {
 	return true
 }
 
-// extractParameterTypes extracts just the parameter types from a procedure's signature or arguments
-// For example: "order_id integer, amount numeric" becomes "integer, numeric"
-func extractParameterTypes(procedure *ir.Procedure) string {
-	// Try to use Arguments field first as it should contain just types
-	if procedure.Arguments != "" {
-		// If Arguments contains parameter names (e.g., "order_id integer, amount numeric"),
-		// extract just the types
-		args := procedure.Arguments
-		if strings.Contains(args, " ") {
-			// This suggests parameter names are included, extract types
-			var types []string
-			params := strings.Split(args, ",")
-			for _, param := range params {
-				param = strings.TrimSpace(param)
-				// Split by spaces and take the last part (the type)
-				parts := strings.Fields(param)
-				if len(parts) >= 2 {
-					// Take the type (usually the second part: "name type")
-					types = append(types, parts[1])
-				} else if len(parts) == 1 {
-					// If only one part, assume it's the type
-					types = append(types, parts[0])
-				}
-			}
-			return strings.Join(types, ", ")
+// formatProcedureParametersForDrop formats procedure parameters for DROP PROCEDURE statements
+// Returns the full parameter signature including mode and name (e.g., "IN order_id integer, IN amount numeric")
+// This is necessary for proper procedure identification in PostgreSQL
+func formatProcedureParametersForDrop(procedure *ir.Procedure) string {
+	// First, try to use the structured Parameters array if available
+	if len(procedure.Parameters) > 0 {
+		var paramParts []string
+		for _, param := range procedure.Parameters {
+			// Use helper function with includeDefault=false for DROP statements
+			paramParts = append(paramParts, formatParameterString(param, false))
 		}
-		// If no spaces, assume Arguments already contains just types
-		return args
+		return strings.Join(paramParts, ", ")
 	}
 
-	// Fallback to Signature field
+	// Fallback to Signature field if Parameters not available
 	if procedure.Signature != "" {
-		var types []string
+		// Signature should already have the mode information
+		// Just need to remove DEFAULT clauses
+		var paramParts []string
 		params := strings.Split(procedure.Signature, ",")
 		for _, param := range params {
 			param = strings.TrimSpace(param)
-			// Remove DEFAULT clauses and extract type
-			if strings.Contains(param, " DEFAULT ") {
-				param = strings.Split(param, " DEFAULT ")[0]
+			// Remove DEFAULT clauses
+			if idx := strings.Index(param, " DEFAULT "); idx != -1 {
+				param = param[:idx]
+			}
+			paramParts = append(paramParts, param)
+		}
+		return strings.Join(paramParts, ", ")
+	}
+
+	// Last resort: try to parse Arguments field and add IN mode
+	if procedure.Arguments != "" {
+		var paramParts []string
+		params := strings.Split(procedure.Arguments, ",")
+		for _, param := range params {
+			param = strings.TrimSpace(param)
+			// Remove DEFAULT clauses
+			if idx := strings.Index(param, " DEFAULT "); idx != -1 {
+				param = param[:idx]
 			}
-			// Split by spaces and take the type part
-			parts := strings.Fields(param)
-			if len(parts) >= 2 {
-				types = append(types, parts[1])
-			} else if len(parts) == 1 {
-				types = append(types, parts[0])
+			// Add IN mode prefix if not already present
+			if !strings.HasPrefix(param, "IN ") && !strings.HasPrefix(param, "OUT ") && !strings.HasPrefix(param, "INOUT ") {
+				param = "IN " + param
 			}
+			paramParts = append(paramParts, param)
 		}
-		return strings.Join(types, ", ")
+		return strings.Join(paramParts, ", ")
 	}
 
 	return ""
diff --git a/ir/inspector.go b/ir/inspector.go
index 3668de8c..9966b2a7 100644
--- a/ir/inspector.go
+++ b/ir/inspector.go
@@ -1170,6 +1170,7 @@ func (i *Inspector) buildFunctions(ctx context.Context, schema *IR, targetSchema
 
 // parseParametersFromSignature parses function signature string into Parameter structs
 // Example signature: "order_id integer, discount_percent numeric DEFAULT 0"
+// Or with modes: "IN order_id integer, OUT result integer"
 func (i *Inspector) parseParametersFromSignature(signature string) []*Parameter {
 	if signature == "" {
 		return nil
@@ -1187,11 +1188,11 @@ func (i *Inspector) parseParametersFromSignature(signature string) []*Parameter
 		}
 
 		param := &Parameter{
-			Mode:     "IN", // Default mode for inspector
+			Mode:     "IN", // Default mode
 			Position: position,
 		}
 
-		// Look for DEFAULT clause
+		// Look for DEFAULT clause first
 		defaultIdx := strings.Index(strings.ToUpper(paramStr), " DEFAULT ")
 		if defaultIdx != -1 {
 			// Extract default value
@@ -1200,14 +1201,28 @@ func (i *Inspector) parseParametersFromSignature(signature string) []*Parameter
 			paramStr = strings.TrimSpace(paramStr[:defaultIdx])
 		}
 
-		// Split into name and type
+		// Split into parts and check for mode prefix
 		parts := strings.Fields(paramStr)
-		if len(parts) >= 2 {
-			param.Name = parts[0]
-			param.DataType = strings.Join(parts[1:], " ")
-		} else if len(parts) == 1 {
-			// Only type, no name (shouldn't happen but handle gracefully)
-			param.DataType = parts[0]
+		if len(parts) == 0 {
+			continue
+		}
+
+		// Check if first part is a mode keyword (IN, OUT, INOUT, VARIADIC, TABLE)
+		firstPart := strings.ToUpper(parts[0])
+		startIdx := 0
+		if firstPart == "IN" || firstPart == "OUT" || firstPart == "INOUT" || firstPart == "VARIADIC" || firstPart == "TABLE" {
+			param.Mode = firstPart
+			startIdx = 1
+		}
+
+		// Parse name and type from remaining parts
+		remainingParts := parts[startIdx:]
+		if len(remainingParts) >= 2 {
+			param.Name = remainingParts[0]
+			param.DataType = strings.Join(remainingParts[1:], " ")
+		} else if len(remainingParts) == 1 {
+			// Only type, no name
+			param.DataType = remainingParts[0]
 		}
 
 		parameters = append(parameters, param)
diff --git a/ir/parser.go b/ir/parser.go
index 5faeb9fd..16f78f65 100644
--- a/ir/parser.go
+++ b/ir/parser.go
@@ -1852,10 +1852,14 @@ func (p *Parser) parseCreateProcedure(funcStmt *pg_query.CreateFunctionStmt) err
 	parameters := p.extractFunctionParametersFromAST(funcStmt)
 
 	// Convert parameters to argument string for Procedure struct
+	// Also build signature with explicit modes
 	var arguments string
+	var signature string
 	if len(parameters) > 0 {
 		var argParts []string
+		var sigParts []string
 		for _, param := range parameters {
+			// For Arguments field (legacy, without mode)
 			if param.Name != "" {
 				argPart := param.Name + " " + param.DataType
 				// Add DEFAULT value if present
@@ -1866,8 +1870,29 @@ func (p *Parser) parseCreateProcedure(funcStmt *pg_query.CreateFunctionStmt) err
 			} else {
 				argParts = append(argParts, param.DataType)
 			}
+
+			// For Signature field (with explicit mode)
+			var sigPart string
+			if param.Mode != "" && param.Mode != "IN" {
+				// Include non-default modes (OUT, INOUT, VARIADIC)
+				sigPart = param.Mode + " "
+			} else {
+				// Include IN mode (default) explicitly to match pg_dump behavior
+				sigPart = "IN "
+			}
+			if param.Name != "" {
+				sigPart += param.Name + " " + param.DataType
+			} else {
+				sigPart += param.DataType
+			}
+			// Add DEFAULT value if present
+			if param.DefaultValue != nil {
+				sigPart += " DEFAULT " + *param.DefaultValue
+			}
+			sigParts = append(sigParts, sigPart)
 		}
 		arguments = strings.Join(argParts, ", ")
+		signature = strings.Join(sigParts, ", ")
 	}
 
 	// Create procedure
@@ -1876,6 +1901,8 @@ func (p *Parser) parseCreateProcedure(funcStmt *pg_query.CreateFunctionStmt) err
 		Name:       procName,
 		Language:   language,
 		Arguments:  arguments,
+		Signature:  signature,
+		Parameters: parameters,
 		Definition: definition,
 	}
 
diff --git a/testdata/diff/create_procedure/add_procedure/diff.sql b/testdata/diff/create_procedure/add_procedure/diff.sql
index 2a5bb85e..5504914b 100644
--- a/testdata/diff/create_procedure/add_procedure/diff.sql
+++ b/testdata/diff/create_procedure/add_procedure/diff.sql
@@ -1,18 +1,11 @@
-CREATE OR REPLACE PROCEDURE update_user_status(
-    user_id integer,
-    new_status text
+CREATE OR REPLACE PROCEDURE example_procedure(
+    IN input_value integer,
+    OUT output_value integer
 )
 LANGUAGE plpgsql
 AS $$
 BEGIN
-    UPDATE users 
-    SET status = new_status, updated_at = NOW() 
-    WHERE id = user_id;
-    
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'User not found: %', user_id;
-    END IF;
-    
-    COMMIT;
+    RAISE NOTICE 'Input value is: %', input_value;
+    output_value := input_value + 1;
 END;
 $$;
diff --git a/testdata/diff/create_procedure/add_procedure/new.sql b/testdata/diff/create_procedure/add_procedure/new.sql
index ab777523..6bdfafdf 100644
--- a/testdata/diff/create_procedure/add_procedure/new.sql
+++ b/testdata/diff/create_procedure/add_procedure/new.sql
@@ -1,18 +1,11 @@
-CREATE PROCEDURE update_user_status(
-    user_id integer,
-    new_status text
+CREATE PROCEDURE example_procedure(
+    IN input_value integer,
+    OUT output_value integer
 )
 LANGUAGE plpgsql
 AS $$
 BEGIN
-    UPDATE users 
-    SET status = new_status, updated_at = NOW() 
-    WHERE id = user_id;
-    
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'User not found: %', user_id;
-    END IF;
-    
-    COMMIT;
+    RAISE NOTICE 'Input value is: %', input_value;
+    output_value := input_value + 1;
 END;
 $$;
\ No newline at end of file
diff --git a/testdata/diff/create_procedure/add_procedure/plan.json b/testdata/diff/create_procedure/add_procedure/plan.json
index 8ef42bdc..4b8af5cb 100644
--- a/testdata/diff/create_procedure/add_procedure/plan.json
+++ b/testdata/diff/create_procedure/add_procedure/plan.json
@@ -1,6 +1,6 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.1.1",
+  "pgschema_version": "1.2.1",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
     "hash": "965b1131737c955e24c7f827c55bd78e4cb49a75adfd04229e0ba297376f5085"
@@ -9,10 +9,10 @@
     {
       "steps": [
         {
-          "sql": "CREATE OR REPLACE PROCEDURE update_user_status(\n    user_id integer,\n    new_status text\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    UPDATE users \n    SET status = new_status, updated_at = NOW() \n    WHERE id = user_id;\n    \n    IF NOT FOUND THEN\n        RAISE EXCEPTION 'User not found: %', user_id;\n    END IF;\n    \n    COMMIT;\nEND;\n$$;",
+          "sql": "CREATE OR REPLACE PROCEDURE example_procedure(\n    IN input_value integer,\n    OUT output_value integer\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    RAISE NOTICE 'Input value is: %', input_value;\n    output_value := input_value + 1;\nEND;\n$$;",
           "type": "procedure",
           "operation": "create",
-          "path": "public.update_user_status"
+          "path": "public.example_procedure"
         }
       ]
     }
diff --git a/testdata/diff/create_procedure/add_procedure/plan.sql b/testdata/diff/create_procedure/add_procedure/plan.sql
index 2a5bb85e..5504914b 100644
--- a/testdata/diff/create_procedure/add_procedure/plan.sql
+++ b/testdata/diff/create_procedure/add_procedure/plan.sql
@@ -1,18 +1,11 @@
-CREATE OR REPLACE PROCEDURE update_user_status(
-    user_id integer,
-    new_status text
+CREATE OR REPLACE PROCEDURE example_procedure(
+    IN input_value integer,
+    OUT output_value integer
 )
 LANGUAGE plpgsql
 AS $$
 BEGIN
-    UPDATE users 
-    SET status = new_status, updated_at = NOW() 
-    WHERE id = user_id;
-    
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'User not found: %', user_id;
-    END IF;
-    
-    COMMIT;
+    RAISE NOTICE 'Input value is: %', input_value;
+    output_value := input_value + 1;
 END;
 $$;
diff --git a/testdata/diff/create_procedure/add_procedure/plan.txt b/testdata/diff/create_procedure/add_procedure/plan.txt
index feeb28f4..832401ca 100644
--- a/testdata/diff/create_procedure/add_procedure/plan.txt
+++ b/testdata/diff/create_procedure/add_procedure/plan.txt
@@ -4,26 +4,19 @@ Summary by type:
   procedures: 1 to add
 
 Procedures:
-  + update_user_status
+  + example_procedure
 
 DDL to be executed:
 --------------------------------------------------
 
-CREATE OR REPLACE PROCEDURE update_user_status(
-    user_id integer,
-    new_status text
+CREATE OR REPLACE PROCEDURE example_procedure(
+    IN input_value integer,
+    OUT output_value integer
 )
 LANGUAGE plpgsql
 AS $$
 BEGIN
-    UPDATE users 
-    SET status = new_status, updated_at = NOW() 
-    WHERE id = user_id;
-    
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'User not found: %', user_id;
-    END IF;
-    
-    COMMIT;
+    RAISE NOTICE 'Input value is: %', input_value;
+    output_value := input_value + 1;
 END;
 $$;
diff --git a/testdata/diff/create_procedure/alter_procedure/diff.sql b/testdata/diff/create_procedure/alter_procedure/diff.sql
index 0f1babfd..11343446 100644
--- a/testdata/diff/create_procedure/alter_procedure/diff.sql
+++ b/testdata/diff/create_procedure/alter_procedure/diff.sql
@@ -1,9 +1,9 @@
-DROP PROCEDURE IF EXISTS process_payment(integer, numeric);
+DROP PROCEDURE IF EXISTS process_payment(IN order_id integer, IN amount numeric);
 
 CREATE OR REPLACE PROCEDURE process_payment(
-    order_id integer,
-    amount numeric,
-    payment_method text DEFAULT 'credit_card'
+    IN order_id integer,
+    IN amount numeric,
+    IN payment_method text DEFAULT 'credit_card'
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/create_procedure/alter_procedure/plan.json b/testdata/diff/create_procedure/alter_procedure/plan.json
index 12b4823c..63baae47 100644
--- a/testdata/diff/create_procedure/alter_procedure/plan.json
+++ b/testdata/diff/create_procedure/alter_procedure/plan.json
@@ -1,21 +1,21 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.1.1",
+  "pgschema_version": "1.2.1",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "ece8114f47983f4d2420a11efca22696d4f85552a24adba54ba0ee342127b045"
+    "hash": "bfc3ecb23e756b22a9efa8a07704b4ec5542c334b76a3338374dc25ea1817d29"
   },
   "groups": [
     {
       "steps": [
         {
-          "sql": "DROP PROCEDURE IF EXISTS process_payment(integer, numeric);",
+          "sql": "DROP PROCEDURE IF EXISTS process_payment(IN order_id integer, IN amount numeric);",
           "type": "procedure",
           "operation": "drop",
           "path": "public.process_payment"
         },
         {
-          "sql": "CREATE OR REPLACE PROCEDURE process_payment(\n    order_id integer,\n    amount numeric,\n    payment_method text DEFAULT 'credit_card'\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    UPDATE orders \n    SET status = 'paid', \n        payment_amount = amount,\n        payment_method = payment_method,\n        processed_at = NOW()\n    WHERE id = order_id;\n    \n    INSERT INTO payment_history (order_id, amount, method, processed_at)\n    VALUES (order_id, amount, payment_method, NOW());\n    \n    COMMIT;\nEND;\n$$;",
+          "sql": "CREATE OR REPLACE PROCEDURE process_payment(\n    IN order_id integer,\n    IN amount numeric,\n    IN payment_method text DEFAULT 'credit_card'\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    UPDATE orders \n    SET status = 'paid', \n        payment_amount = amount,\n        payment_method = payment_method,\n        processed_at = NOW()\n    WHERE id = order_id;\n    \n    INSERT INTO payment_history (order_id, amount, method, processed_at)\n    VALUES (order_id, amount, payment_method, NOW());\n    \n    COMMIT;\nEND;\n$$;",
           "type": "procedure",
           "operation": "create",
           "path": "public.process_payment"
diff --git a/testdata/diff/create_procedure/alter_procedure/plan.sql b/testdata/diff/create_procedure/alter_procedure/plan.sql
index 0f1babfd..11343446 100644
--- a/testdata/diff/create_procedure/alter_procedure/plan.sql
+++ b/testdata/diff/create_procedure/alter_procedure/plan.sql
@@ -1,9 +1,9 @@
-DROP PROCEDURE IF EXISTS process_payment(integer, numeric);
+DROP PROCEDURE IF EXISTS process_payment(IN order_id integer, IN amount numeric);
 
 CREATE OR REPLACE PROCEDURE process_payment(
-    order_id integer,
-    amount numeric,
-    payment_method text DEFAULT 'credit_card'
+    IN order_id integer,
+    IN amount numeric,
+    IN payment_method text DEFAULT 'credit_card'
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/create_procedure/alter_procedure/plan.txt b/testdata/diff/create_procedure/alter_procedure/plan.txt
index 3907f71c..88b369ca 100644
--- a/testdata/diff/create_procedure/alter_procedure/plan.txt
+++ b/testdata/diff/create_procedure/alter_procedure/plan.txt
@@ -10,12 +10,12 @@ Procedures:
 DDL to be executed:
 --------------------------------------------------
 
-DROP PROCEDURE IF EXISTS process_payment(integer, numeric);
+DROP PROCEDURE IF EXISTS process_payment(IN order_id integer, IN amount numeric);
 
 CREATE OR REPLACE PROCEDURE process_payment(
-    order_id integer,
-    amount numeric,
-    payment_method text DEFAULT 'credit_card'
+    IN order_id integer,
+    IN amount numeric,
+    IN payment_method text DEFAULT 'credit_card'
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/create_procedure/drop_procedure/diff.sql b/testdata/diff/create_procedure/drop_procedure/diff.sql
index 647565fd..d69f3bf6 100644
--- a/testdata/diff/create_procedure/drop_procedure/diff.sql
+++ b/testdata/diff/create_procedure/drop_procedure/diff.sql
@@ -1 +1 @@
-DROP PROCEDURE IF EXISTS cleanup_old_data(integer);
+DROP PROCEDURE IF EXISTS cleanup_old_data(IN days_old integer);
diff --git a/testdata/diff/create_procedure/drop_procedure/plan.json b/testdata/diff/create_procedure/drop_procedure/plan.json
index 720862f3..46abd99f 100644
--- a/testdata/diff/create_procedure/drop_procedure/plan.json
+++ b/testdata/diff/create_procedure/drop_procedure/plan.json
@@ -1,15 +1,15 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.1.1",
+  "pgschema_version": "1.2.1",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "f02c22162ec7f808d4acf04c1cd694d8fe513c30c21845ab600e8eca2b4f2752"
+    "hash": "53ad909d589a920e0f96183fa15eefd1ad2889fdcc64d7486cb100eb507a9055"
   },
   "groups": [
     {
       "steps": [
         {
-          "sql": "DROP PROCEDURE IF EXISTS cleanup_old_data(integer);",
+          "sql": "DROP PROCEDURE IF EXISTS cleanup_old_data(IN days_old integer);",
           "type": "procedure",
           "operation": "drop",
           "path": "public.cleanup_old_data"
diff --git a/testdata/diff/create_procedure/drop_procedure/plan.sql b/testdata/diff/create_procedure/drop_procedure/plan.sql
index 647565fd..d69f3bf6 100644
--- a/testdata/diff/create_procedure/drop_procedure/plan.sql
+++ b/testdata/diff/create_procedure/drop_procedure/plan.sql
@@ -1 +1 @@
-DROP PROCEDURE IF EXISTS cleanup_old_data(integer);
+DROP PROCEDURE IF EXISTS cleanup_old_data(IN days_old integer);
diff --git a/testdata/diff/create_procedure/drop_procedure/plan.txt b/testdata/diff/create_procedure/drop_procedure/plan.txt
index da857ece..266db5d9 100644
--- a/testdata/diff/create_procedure/drop_procedure/plan.txt
+++ b/testdata/diff/create_procedure/drop_procedure/plan.txt
@@ -9,4 +9,4 @@ Procedures:
 DDL to be executed:
 --------------------------------------------------
 
-DROP PROCEDURE IF EXISTS cleanup_old_data(integer);
+DROP PROCEDURE IF EXISTS cleanup_old_data(IN days_old integer);
diff --git a/testdata/diff/migrate/v4/diff.sql b/testdata/diff/migrate/v4/diff.sql
index 526ad887..7a220cf3 100644
--- a/testdata/diff/migrate/v4/diff.sql
+++ b/testdata/diff/migrate/v4/diff.sql
@@ -1,6 +1,6 @@
 CREATE OR REPLACE PROCEDURE simple_salary_update(
-    p_emp_no integer,
-    p_amount integer
+    IN p_emp_no integer,
+    IN p_amount integer
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/migrate/v4/plan.json b/testdata/diff/migrate/v4/plan.json
index b68d9c3d..d1f2a1b7 100644
--- a/testdata/diff/migrate/v4/plan.json
+++ b/testdata/diff/migrate/v4/plan.json
@@ -1,6 +1,6 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.0.0",
+  "pgschema_version": "1.2.1",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
     "hash": "953c5263c9185d170429fab8c78931f7801f8479579faf963c0ac9635bf2a8ed"
@@ -9,7 +9,7 @@
     {
       "steps": [
         {
-          "sql": "CREATE OR REPLACE PROCEDURE simple_salary_update(\n    p_emp_no integer,\n    p_amount integer\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    -- Simple update of salary amount\n    UPDATE salary \n    SET amount = p_amount \n    WHERE emp_no = p_emp_no \n    AND to_date = '9999-01-01';\n    \n    RAISE NOTICE 'Updated salary for employee % to $%', p_emp_no, p_amount;\nEND;\n$$;",
+          "sql": "CREATE OR REPLACE PROCEDURE simple_salary_update(\n    IN p_emp_no integer,\n    IN p_amount integer\n)\nLANGUAGE plpgsql\nAS $$\nBEGIN\n    -- Simple update of salary amount\n    UPDATE salary \n    SET amount = p_amount \n    WHERE emp_no = p_emp_no \n    AND to_date = '9999-01-01';\n    \n    RAISE NOTICE 'Updated salary for employee % to $%', p_emp_no, p_amount;\nEND;\n$$;",
           "type": "procedure",
           "operation": "create",
           "path": "public.simple_salary_update"
diff --git a/testdata/diff/migrate/v4/plan.sql b/testdata/diff/migrate/v4/plan.sql
index fa84bc16..fb6a559d 100644
--- a/testdata/diff/migrate/v4/plan.sql
+++ b/testdata/diff/migrate/v4/plan.sql
@@ -1,6 +1,6 @@
 CREATE OR REPLACE PROCEDURE simple_salary_update(
-    p_emp_no integer,
-    p_amount integer
+    IN p_emp_no integer,
+    IN p_amount integer
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/migrate/v4/plan.txt b/testdata/diff/migrate/v4/plan.txt
index c16512b4..614d285a 100644
--- a/testdata/diff/migrate/v4/plan.txt
+++ b/testdata/diff/migrate/v4/plan.txt
@@ -28,8 +28,8 @@ DDL to be executed:
 
 -- Transaction Group #1
 CREATE OR REPLACE PROCEDURE simple_salary_update(
-    p_emp_no integer,
-    p_amount integer
+    IN p_emp_no integer,
+    IN p_amount integer
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/diff/migrate/v5/diff.sql b/testdata/diff/migrate/v5/diff.sql
index dd92355c..a33897e8 100644
--- a/testdata/diff/migrate/v5/diff.sql
+++ b/testdata/diff/migrate/v5/diff.sql
@@ -1,4 +1,4 @@
-DROP PROCEDURE IF EXISTS simple_salary_update(integer, integer);
+DROP PROCEDURE IF EXISTS simple_salary_update(IN p_emp_no integer, IN p_amount integer);
 
 DROP TABLE IF EXISTS title CASCADE;
 
diff --git a/testdata/diff/migrate/v5/plan.json b/testdata/diff/migrate/v5/plan.json
index 13b320f0..4772b519 100644
--- a/testdata/diff/migrate/v5/plan.json
+++ b/testdata/diff/migrate/v5/plan.json
@@ -1,15 +1,15 @@
 {
   "version": "1.0.0",
-  "pgschema_version": "1.1.1",
+  "pgschema_version": "1.2.1",
   "created_at": "1970-01-01T00:00:00Z",
   "source_fingerprint": {
-    "hash": "d9d1c4acba93820180b7c890e1673d3e722c842c93c0bd42c2bd0b038d68681c"
+    "hash": "d9c2bda9bd3597eeee9005abe7e103ffd05e19890772c5c5f28e0a6020018942"
   },
   "groups": [
     {
       "steps": [
         {
-          "sql": "DROP PROCEDURE IF EXISTS simple_salary_update(integer, integer);",
+          "sql": "DROP PROCEDURE IF EXISTS simple_salary_update(IN p_emp_no integer, IN p_amount integer);",
           "type": "procedure",
           "operation": "drop",
           "path": "public.simple_salary_update"
diff --git a/testdata/diff/migrate/v5/plan.sql b/testdata/diff/migrate/v5/plan.sql
index dd92355c..a33897e8 100644
--- a/testdata/diff/migrate/v5/plan.sql
+++ b/testdata/diff/migrate/v5/plan.sql
@@ -1,4 +1,4 @@
-DROP PROCEDURE IF EXISTS simple_salary_update(integer, integer);
+DROP PROCEDURE IF EXISTS simple_salary_update(IN p_emp_no integer, IN p_amount integer);
 
 DROP TABLE IF EXISTS title CASCADE;
 
diff --git a/testdata/diff/migrate/v5/plan.txt b/testdata/diff/migrate/v5/plan.txt
index f885e362..9f954c82 100644
--- a/testdata/diff/migrate/v5/plan.txt
+++ b/testdata/diff/migrate/v5/plan.txt
@@ -28,7 +28,7 @@ Tables:
 DDL to be executed:
 --------------------------------------------------
 
-DROP PROCEDURE IF EXISTS simple_salary_update(integer, integer);
+DROP PROCEDURE IF EXISTS simple_salary_update(IN p_emp_no integer, IN p_amount integer);
 
 DROP TABLE IF EXISTS title CASCADE;
 
diff --git a/testdata/dump/employee/pgschema.sql b/testdata/dump/employee/pgschema.sql
index 80425b90..9afa95e4 100644
--- a/testdata/dump/employee/pgschema.sql
+++ b/testdata/dump/employee/pgschema.sql
@@ -189,8 +189,8 @@ $$;
 --
 
 CREATE OR REPLACE PROCEDURE simple_salary_update(
-    p_emp_no integer,
-    p_amount integer
+    IN p_emp_no integer,
+    IN p_amount integer
 )
 LANGUAGE plpgsql
 AS $$
diff --git a/testdata/include/expected_full_schema.sql b/testdata/include/expected_full_schema.sql
index ec3d34cc..73e83e2c 100644
--- a/testdata/include/expected_full_schema.sql
+++ b/testdata/include/expected_full_schema.sql
@@ -197,8 +197,8 @@ $$;
 --
 
 CREATE OR REPLACE PROCEDURE update_status(
-    user_id_param integer,
-    new_status text
+    IN user_id_param integer,
+    IN new_status text
 )
 LANGUAGE sql
 AS $$
diff --git a/testdata/include/procedures/update_status.sql b/testdata/include/procedures/update_status.sql
index a9d23ec1..f63137ed 100644
--- a/testdata/include/procedures/update_status.sql
+++ b/testdata/include/procedures/update_status.sql
@@ -3,8 +3,8 @@
 --
 
 CREATE OR REPLACE PROCEDURE update_status(
-    user_id_param integer,
-    new_status text
+    IN user_id_param integer,
+    IN new_status text
 )
 LANGUAGE sql
 AS $$