diff --git a/package.json b/package.json
index 9f616dc..f7ecb69 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "engines": {
     "node": ">=16"
   },
-  "version": "5.4.0",
+  "version": "5.4.1",
   "type": "module",
   "description": "A GLSL ES 1.0 and 3.0 parser and preprocessor that can preserve whitespace and comments",
   "scripts": {
diff --git a/src/parser/scope.test.ts b/src/parser/scope.test.ts
index 6499050..030ddbe 100644
--- a/src/parser/scope.test.ts
+++ b/src/parser/scope.test.ts
@@ -572,3 +572,18 @@ void main() {
   const a = Object.values(ast.scopes[0].functions.a)[0];
   expect(a.references).toHaveLength(3);
 });
+
+test('rename function prototypes', () => {
+  const ast = c.parseSrc(
+    `vec3 hash3(vec3 p3);
+vec3 hash3(vec3 p3) {}`
+  );
+
+  ast.scopes[0].functions = renameFunctions(
+    ast.scopes[0].functions,
+    (name) => `${name}_FUNCTION`
+  );
+
+  expect(generate(ast)).toBe(`vec3 hash3_FUNCTION(vec3 p3);
+vec3 hash3_FUNCTION(vec3 p3) {}`);
+});
diff --git a/src/parser/utils.ts b/src/parser/utils.ts
index 86a9c62..63705cc 100644
--- a/src/parser/utils.ts
+++ b/src/parser/utils.ts
@@ -100,6 +100,8 @@ export const renameFunction = (
         node.identifier.type === 'identifier'
       ) {
         node.identifier.identifier = newName;
+      } else if (node.type === 'function_prototype') {
+        node.header.name.identifier = newName;
       } else {
         console.warn('Unknown function node to rename', node);
         throw new Error(`Function for type ${node.type} not recognized`);