diff --git a/pkgs/ffigen/lib/src/code_generator/objc_protocol.dart b/pkgs/ffigen/lib/src/code_generator/objc_protocol.dart
index cca7da841..0c0eeb882 100644
--- a/pkgs/ffigen/lib/src/code_generator/objc_protocol.dart
+++ b/pkgs/ffigen/lib/src/code_generator/objc_protocol.dart
@@ -164,10 +164,10 @@ ${makeDartDoc(dartDoc ?? originalName)}abstract final class $name {
 
   @override
   BindingString? toObjCBindingString(Writer w) {
-    final wrapperName = builtInFunctions.wrapperName;
+    final wrapName = builtInFunctions.wrapperName;
     final mainString = '''
 
-Protocol* _${wrapperName}_$originalName() { return @protocol($originalName); }
+Protocol* _${wrapName}_$originalName(void) { return @protocol($originalName); }
 ''';
 
     return BindingString(
diff --git a/pkgs/objective_c/src/objective_c_bindings_generated.m b/pkgs/objective_c/src/objective_c_bindings_generated.m
index 80ce85af1..df52bfe84 100644
--- a/pkgs/objective_c/src/objective_c_bindings_generated.m
+++ b/pkgs/objective_c/src/objective_c_bindings_generated.m
@@ -10,7 +10,7 @@
 id objc_retain(id);
 id objc_retainBlock(id);
 
-Protocol* _ObjectiveCBindings_NSStreamDelegate() { return @protocol(NSStreamDelegate); }
+Protocol* _ObjectiveCBindings_NSStreamDelegate(void) { return @protocol(NSStreamDelegate); }
 
 typedef void  (^_ListenerTrampoline)(id arg0, id arg1, id arg2);
 __attribute__((visibility("default"))) __attribute__((used))
diff --git a/pkgs/objective_c/src/objective_c_runtime.h b/pkgs/objective_c/src/objective_c_runtime.h
index 3849ccd55..f911c549f 100644
--- a/pkgs/objective_c/src/objective_c_runtime.h
+++ b/pkgs/objective_c/src/objective_c_runtime.h
@@ -27,9 +27,9 @@ ObjCObject** objc_copyClassList(unsigned int* count);
 
 // The signature of this function is just a placeholder. This function is used
 // by every method invocation, and is cast to every signature we need.
-void objc_msgSend();
-void objc_msgSend_fpret();
-void objc_msgSend_stret();
+void objc_msgSend(void);
+void objc_msgSend_fpret(void);
+void objc_msgSend_stret(void);
 
 // See https://clang.llvm.org/docs/Block-ABI-Apple.html
 typedef struct _ObjCBlockDesc {