diff --git a/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs b/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
index 35e03b4f75c..e1ab4aaf699 100644
--- a/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
+++ b/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
@@ -831,22 +831,28 @@ fn type_check_trait_implementation(
                         None,
                     ),
                 };
-                trait_type_mapping.extend(&TypeSubstMap::from_type_parameters_and_type_arguments(
-                    vec![type_engine.insert(
-                        engines,
-                        old_type_decl_info1,
-                        type_decl.name.span().source_id(),
-                    )],
-                    vec![type_decl.ty.clone().unwrap().type_id],
-                ));
-                trait_type_mapping.extend(&TypeSubstMap::from_type_parameters_and_type_arguments(
-                    vec![type_engine.insert(
-                        engines,
-                        old_type_decl_info2,
-                        type_decl.name.span().source_id(),
-                    )],
-                    vec![type_decl.ty.clone().unwrap().type_id],
-                ));
+                if let Some(type_arg) = type_decl.ty.clone() {
+                    trait_type_mapping.extend(
+                        &TypeSubstMap::from_type_parameters_and_type_arguments(
+                            vec![type_engine.insert(
+                                engines,
+                                old_type_decl_info1,
+                                type_decl.name.span().source_id(),
+                            )],
+                            vec![type_arg.type_id],
+                        ),
+                    );
+                    trait_type_mapping.extend(
+                        &TypeSubstMap::from_type_parameters_and_type_arguments(
+                            vec![type_engine.insert(
+                                engines,
+                                old_type_decl_info2,
+                                type_decl.name.span().source_id(),
+                            )],
+                            vec![type_arg.type_id],
+                        ),
+                    );
+                }
             }
         }
     }
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.lock
new file mode 100644
index 00000000000..d6d5627a81d
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.lock
@@ -0,0 +1,3 @@
+[[package]]
+name = "associated_type_not_in_trait"
+source = "member"
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.toml
new file mode 100644
index 00000000000..800719114d2
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/Forc.toml
@@ -0,0 +1,6 @@
+[project]
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "associated_type_not_in_trait"
+implicit-std = false
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/src/main.sw
new file mode 100644
index 00000000000..5a1f41599ba
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/src/main.sw
@@ -0,0 +1,4 @@
+script;
+trait Trait{}
+struct Struct0{}
+impl Trait for Struct0{type u;const u=0;}
\ No newline at end of file
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/test.toml b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/test.toml
new file mode 100644
index 00000000000..74ffd8a5f62
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/associated_type_not_in_trait/test.toml
@@ -0,0 +1,3 @@
+category = "fail"
+
+# check: $()Type "u" is not a part of trait "Trait"'s interface surface.