diff --git a/CMakeLists.txt b/CMakeLists.txt
index d5e032400e..ac9bb20326 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -358,6 +358,11 @@ else ()
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-error=objc-method-access")
     endif()
 
+    # Clang -Wmissing-declarations differs from GCC, set -Wmissing-prototypes for parity
+    if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wmissing-prototypes")
+    endif()
+
     # On mingw all code is already PIC, this will avoid compiler error on redefining this option
     if (NOT MINGW)
         set(CMAKE_POSITION_INDEPENDENT_CODE ON)
diff --git a/src/openrct2/Version.cpp b/src/openrct2/Version.cpp
index d88beed61b..37dffddad7 100644
--- a/src/openrct2/Version.cpp
+++ b/src/openrct2/Version.cpp
@@ -56,13 +56,19 @@ const char gVersionInfoFull[] = OPENRCT2_NAME ", "
     ;
 
 #ifdef __EMSCRIPTEN__
-// This must be wrapped in extern "C", according to the emscripten docs, "to prevent C++ name mangling"
+    // This must be wrapped in extern "C", according to the emscripten docs, "to prevent C++ name mangling"
+    // Ignore -Wmissing-prototypes here, see https://github.com/llvm/llvm-project/issues/94138
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wmissing-prototypes"
+
 extern "C" {
 const char* GetVersion()
 {
     return gVersionInfoFull;
 }
 }
+
+    #pragma clang diagnostic pop
 #endif
 
 NewVersionInfo GetLatestVersion()
diff --git a/src/openrct2/platform/Platform.macOS.mm b/src/openrct2/platform/Platform.macOS.mm
index 2d412b56de..5235e0884f 100644
--- a/src/openrct2/platform/Platform.macOS.mm
+++ b/src/openrct2/platform/Platform.macOS.mm
@@ -155,7 +155,7 @@ namespace OpenRCT2::Platform
         return false;
     }
 
-    bool HasMatchingLanguage(NSString* preferredLocale, uint16_t* languageIdentifier)
+    static bool HasMatchingLanguage(NSString* preferredLocale, uint16_t* languageIdentifier)
     {
         @autoreleasepool
         {