diff --git a/src/modules/flow/string/string-icu.c b/src/modules/flow/string/string-icu.c
index 8138b80bb..664c46f85 100644
--- a/src/modules/flow/string/string-icu.c
+++ b/src/modules/flow/string/string-icu.c
@@ -842,7 +842,7 @@ string_change_case(struct sol_flow_node *node,
     if (!u_lower) {
         errno = ENOMEM;
         free(u_orig);
-        sol_flow_send_error_packet(node, errno, "Out of memory");
+        sol_flow_send_error_packet_errno(node, errno);
         return -errno;
     }
 
@@ -860,7 +860,7 @@ string_change_case(struct sol_flow_node *node,
     if (r < 0) {
         free(u_orig);
         free(u_lower);
-        sol_flow_send_error_packet(node, -r, "%s", u_errorName(err));
+        sol_flow_send_error_packet_str(node, -r, u_errorName(err));
         return r;
     }
 
diff --git a/src/modules/flow/switcher/switcher.c b/src/modules/flow/switcher/switcher.c
index cb4a606aa..1bc8838b2 100644
--- a/src/modules/flow/switcher/switcher.c
+++ b/src/modules/flow/switcher/switcher.c
@@ -219,7 +219,7 @@ error_forward(struct sol_flow_node *node, void *data, uint16_t port, uint16_t co
     r = sol_flow_packet_get_error(packet, &code_value, &msg);
     SOL_INT_CHECK(r, < 0, r);
 
-    return sol_flow_send_error_packet(node, code_value, "%s", msg);
+    return sol_flow_send_error_packet_str(node, code_value, msg);
 }
 
 static int
diff --git a/src/test-fbp/converter-error.fbp b/src/test-fbp/converter-error.fbp
index ea4ff58bc..f82ef35d9 100644
--- a/src/test-fbp/converter-error.fbp
+++ b/src/test-fbp/converter-error.fbp
@@ -30,7 +30,7 @@
 
 conv_error(converter/error)
 const_error_code(constant/int:value=33)
-const_error_msg(constant/string:value="Numerical argument out of domain")
+const_error_msg(constant/string:value="Numerical argument out of domain (errno 33)")
 const_int(constant/int:value=10)
 const_zero(constant/int:value=0)
 error_msg_equal(string/compare)
diff --git a/src/test-fbp/switcher-simple-forward.fbp b/src/test-fbp/switcher-simple-forward.fbp
index 2ff8d0c24..ee530c0b9 100644
--- a/src/test-fbp/switcher-simple-forward.fbp
+++ b/src/test-fbp/switcher-simple-forward.fbp
@@ -37,7 +37,7 @@ const_int(constant/int:value=10)
 const_rgb(constant/rgb:value=255|10|100)
 const_direction_vector(constant/direction-vector:value=255|10|100)
 const_string(constant/string:value="Hello")
-const_error(constant/string:value="Numerical argument out of domain")
+const_error(constant/string:value="Numerical argument out of domain (errno 33)")
 const_timestamp(constant/string:value="2016-09-23T09:30:00")
 conv_timestamp(converter/string-to-timestamp)
 conv_timestamp_str(converter/timestamp-to-string:format="%Y-%m-%dT%H:%M:%S")