diff --git a/GCDWebServer.xcodeproj/project.pbxproj b/GCDWebServer.xcodeproj/project.pbxproj
index 39ca8cc..08531ed 100644
--- a/GCDWebServer.xcodeproj/project.pbxproj
+++ b/GCDWebServer.xcodeproj/project.pbxproj
@@ -1223,6 +1223,7 @@
 					"-Weverything",
 					"-Wshadow",
 					"-Wshorten-64-to-32",
+					"-Wstrict-prototypes",
 					"-Wno-vla",
 					"-Wno-explicit-ownership-type",
 					"-Wno-gnu-statement-expression",
diff --git a/GCDWebServer/Core/GCDWebServerPrivate.h b/GCDWebServer/Core/GCDWebServerPrivate.h
index d485304..feea314 100644
--- a/GCDWebServer/Core/GCDWebServerPrivate.h
+++ b/GCDWebServer/Core/GCDWebServerPrivate.h
@@ -170,7 +170,7 @@ static inline NSError* GCDWebServerMakePosixError(int code) {
   return [NSError errorWithDomain:NSPOSIXErrorDomain code:code userInfo:@{NSLocalizedDescriptionKey : (NSString*)[NSString stringWithUTF8String:strerror(code)]}];
 }
 
-extern void GCDWebServerInitializeFunctions();
+extern void GCDWebServerInitializeFunctions(void);
 extern NSString* _Nullable GCDWebServerNormalizeHeaderValue(NSString* _Nullable value);
 extern NSString* _Nullable GCDWebServerTruncateHeaderValue(NSString* _Nullable value);
 extern NSString* _Nullable GCDWebServerExtractHeaderValueParameter(NSString* _Nullable value, NSString* attribute);