diff --git a/code/go/dse/ast/Simulation.go b/code/go/dse/ast/Simulation.go
index b272309..99b0213 100644
--- a/code/go/dse/ast/Simulation.go
+++ b/code/go/dse/ast/Simulation.go
@@ -18,8 +18,8 @@ type Model struct {
 	Workflows *[]Workflow    `yaml:"workflows,omitempty"`
 }
 type ModelChannel struct {
-	Alias *string `yaml:"alias,omitempty"`
-	Name  string  `yaml:"name"`
+	Alias string `yaml:"alias"`
+	Name  string `yaml:"name"`
 }
 type Simulation struct {
 	Kind     SimulationKind  `yaml:"kind"`
diff --git a/doc/content/schemas/yaml/Simulation.md b/doc/content/schemas/yaml/Simulation.md
index fef549c..b559367 100644
--- a/doc/content/schemas/yaml/Simulation.md
+++ b/doc/content/schemas/yaml/Simulation.md
@@ -204,7 +204,7 @@ A model <-> simulation channel mapping.
 |Name|Type|Required|Description|
 |---|---|---|---|
 |name|string|true|The name of the channel in the simulation.|
-|alias|string|false|The name (alias) of the channel in the model.|
+|alias|string|true|The name (alias) of the channel in the model.|
 
 <h2 id="tocS_Uses">Uses</h2>
 
diff --git a/schemas/yaml/Simulation.yaml b/schemas/yaml/Simulation.yaml
index 901f920..1d0398c 100644
--- a/schemas/yaml/Simulation.yaml
+++ b/schemas/yaml/Simulation.yaml
@@ -143,6 +143,7 @@ components:
       description: A model <-> simulation channel mapping.
       required:
         - name
+        - alias
       properties:
         name:
           type: string