diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1f1adcb..be4b584 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -30,10 +30,7 @@ endmacro()
 
 xcheck_add_c_compiler_flag(-Wall)
 xcheck_add_c_compiler_flag(-Werror)
-# -Wextra is too spartan on GCC
-if(CMAKE_C_COMPILER_ID MATCHES "AppleClang|Clang")
-    add_compile_options(-Wextra)
-endif()
+xcheck_add_c_compiler_flag(-Wextra)
 xcheck_add_c_compiler_flag(-Wno-sign-compare)
 xcheck_add_c_compiler_flag(-Wno-missing-field-initializers)
 xcheck_add_c_compiler_flag(-Wno-unused-parameter)
diff --git a/quickjs.c b/quickjs.c
index 7b2f461..9e76e90 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -13530,8 +13530,10 @@ static __exception int js_append_enumerate(JSContext *ctx, JSValue *sp)
     iterator = JS_GetProperty(ctx, sp[-1], JS_ATOM_Symbol_iterator);
     if (JS_IsException(iterator))
         return -1;
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft = { .generic_magic = js_create_array_iterator };
     is_array_iterator = JS_IsCFunction(ctx, iterator,
-                                       (JSCFunction *)js_create_array_iterator,
+                                       ft.generic,
                                        JS_ITERATOR_KIND_VALUE);
     JS_FreeValue(ctx, iterator);
 
@@ -13543,9 +13545,11 @@ static __exception int js_append_enumerate(JSContext *ctx, JSValue *sp)
         JS_FreeValue(ctx, enumobj);
         return -1;
     }
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft2 = { .iterator_next = js_array_iterator_next };
     if (is_array_iterator
-    &&  JS_IsCFunction(ctx, method, (JSCFunction *)js_array_iterator_next, 0)
-    &&  js_get_fast_array(ctx, sp[-1], &arrp, &count32)) {
+            &&  JS_IsCFunction(ctx, method, ft2.generic, 0)
+            &&  js_get_fast_array(ctx, sp[-1], &arrp, &count32)) {
         uint32_t len;
         if (js_get_length32(ctx, &len, sp[-1]))
             goto exception;
@@ -45605,9 +45609,13 @@ void JS_AddIntrinsicPromise(JSContext *ctx)
     JS_NewGlobalCConstructor2(ctx, obj1, "Promise",
                               ctx->class_proto[JS_CLASS_PROMISE]);
 
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft;
+
     /* AsyncFunction */
     ctx->class_proto[JS_CLASS_ASYNC_FUNCTION] = JS_NewObjectProto(ctx, ctx->function_proto);
-    obj1 = JS_NewCFunction3(ctx, (JSCFunction *)js_function_constructor,
+    ft.generic_magic = js_function_constructor;
+    obj1 = JS_NewCFunction3(ctx, ft.generic,
                             "AsyncFunction", 1,
                             JS_CFUNC_constructor_or_func_magic, JS_FUNC_ASYNC,
                             ctx->function_ctor);
@@ -45643,7 +45651,8 @@ void JS_AddIntrinsicPromise(JSContext *ctx)
     /* AsyncGeneratorFunction */
     ctx->class_proto[JS_CLASS_ASYNC_GENERATOR_FUNCTION] =
         JS_NewObjectProto(ctx, ctx->function_proto);
-    obj1 = JS_NewCFunction3(ctx, (JSCFunction *)js_function_constructor,
+    ft.generic_magic = js_function_constructor;
+    obj1 = JS_NewCFunction3(ctx, ft.generic,
                             "AsyncGeneratorFunction", 1,
                             JS_CFUNC_constructor_or_func_magic,
                             JS_FUNC_ASYNC_GENERATOR,
@@ -47180,11 +47189,13 @@ void JS_AddIntrinsicBaseObjects(JSContext *ctx)
     JS_NewGlobalCConstructor2(ctx, obj1,
                               "Error", ctx->class_proto[JS_CLASS_ERROR]);
 
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft = { .generic_magic = js_error_constructor };
     for(i = 0; i < JS_NATIVE_ERROR_COUNT; i++) {
         JSValue func_obj;
         int n_args;
         n_args = 1 + (i == JS_AGGREGATE_ERROR);
-        func_obj = JS_NewCFunction3(ctx, (JSCFunction *)js_error_constructor,
+        func_obj = JS_NewCFunction3(ctx, ft.generic,
                                     native_error_name[i], n_args,
                                     JS_CFUNC_constructor_or_func_magic, i, obj1);
         JS_NewGlobalCConstructor2(ctx, func_obj, native_error_name[i],
@@ -50344,6 +50355,8 @@ void JS_AddIntrinsicTypedArrays(JSContext *ctx)
                                countof(js_typed_array_base_funcs));
     JS_SetConstructor(ctx, typed_array_base_func, typed_array_base_proto);
 
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft = { .generic_magic = js_typed_array_constructor };
     for(i = JS_CLASS_UINT8C_ARRAY; i < JS_CLASS_UINT8C_ARRAY + JS_TYPED_ARRAY_COUNT; i++) {
         JSValue func_obj;
         char buf[ATOM_GET_STR_BUF_SIZE];
@@ -50356,7 +50369,7 @@ void JS_AddIntrinsicTypedArrays(JSContext *ctx)
                                   0);
         name = JS_AtomGetStr(ctx, buf, sizeof(buf),
                              JS_ATOM_Uint8ClampedArray + i - JS_CLASS_UINT8C_ARRAY);
-        func_obj = JS_NewCFunction3(ctx, (JSCFunction *)js_typed_array_constructor,
+        func_obj = JS_NewCFunction3(ctx, ft.generic,
                                     name, 3, JS_CFUNC_constructor_magic, i,
                                     typed_array_base_func);
         JS_NewGlobalCConstructor2(ctx, func_obj, name, ctx->class_proto[i]);
diff --git a/quickjs.h b/quickjs.h
index f85eb89..ba6e9f5 100644
--- a/quickjs.h
+++ b/quickjs.h
@@ -916,7 +916,9 @@ static inline JSValue JS_NewCFunctionMagic(JSContext *ctx, JSCFunctionMagic *fun
                                            const char *name,
                                            int length, JSCFunctionEnum cproto, int magic)
 {
-    return JS_NewCFunction2(ctx, (JSCFunction *)func, name, length, cproto, magic);
+    /* Used to squelch a -Wcast-function-type warning. */
+    JSCFunctionType ft = { .generic_magic = func };
+    return JS_NewCFunction2(ctx, ft.generic, name, length, cproto, magic);
 }
 void JS_SetConstructor(JSContext *ctx, JSValueConst func_obj,
                        JSValueConst proto);