diff --git a/source/slang/slang-check-modifier.cpp b/source/slang/slang-check-modifier.cpp
index 8be5dc39bf0..0cc5cb55714 100644
--- a/source/slang/slang-check-modifier.cpp
+++ b/source/slang/slang-check-modifier.cpp
@@ -1531,7 +1531,11 @@ bool isModifierAllowedOnDecl(bool isGLSLInput, ASTNodeType modifierType, Decl* d
     case ASTNodeType::DynModifier:
         return as<InterfaceDecl>(decl) || as<VarDecl>(decl) || as<ParamDecl>(decl);
     case ASTNodeType::OverrideModifier:
-        return as<FunctionDeclBase>(decl) && as<AggTypeDecl>(getParentDecl(decl));
+        {
+            Decl* parent = getParentDecl(decl);
+            return as<FunctionDeclBase>(decl) &&
+                   (as<AggTypeDecl>(parent) || as<ExtensionDecl>(parent));
+        }
     default:
         return true;
     }
diff --git a/tests/language-feature/interfaces/override-default-method.slang b/tests/language-feature/interfaces/override-default-method.slang
index 22ae483118e..c46f2865b16 100644
--- a/tests/language-feature/interfaces/override-default-method.slang
+++ b/tests/language-feature/interfaces/override-default-method.slang
@@ -25,6 +25,25 @@ struct Impl : IFoo
     }
 }
 
+struct Other
+{
+    int n;
+}
+
+extension Other: IFoo
+{
+    int getVal()
+    {
+        return n;
+    }
+
+    // Override should also work inside an extension
+    override int getGreaterVal<int x>()
+    {
+        return getVal() + x + 2;
+    }
+}
+
 int test<T:IFoo>(T v) { return v.getGreaterVal<1>(); }
 
 //TEST_INPUT: set resultBuffer = out ubuffer(data=[0 0 0 0], stride=4)
@@ -37,4 +56,8 @@ void computeMain()
     int result = test(impl);
     resultBuffer[0] = result;
     // CHECK: 44
-}
\ No newline at end of file
+
+    Other other = {32};
+    resultBuffer[1] = test(other);
+    // CHECK-NEXT: 35
+}