diff --git a/src/3rdparty/masm/wtf/Compiler.h b/src/3rdparty/masm/wtf/Compiler.h
index 598d7f2c1c..a6c1fe9419 100644
--- a/src/3rdparty/masm/wtf/Compiler.h
+++ b/src/3rdparty/masm/wtf/Compiler.h
@@ -27,13 +27,13 @@
 #define WTF_Compiler_h
 
 /* COMPILER() - the compiler being used to build the project */
-#define COMPILER(WTF_FEATURE) WTF_COMPILER_##WTF_FEATURE
+#define COMPILER(WTF_FEATURE) (defined WTF_COMPILER_##WTF_FEATURE && WTF_COMPILER_##WTF_FEATURE)
 
 /* COMPILER_SUPPORTS() - whether the compiler being used to build the project supports the given feature. */
-#define COMPILER_SUPPORTS(WTF_COMPILER_FEATURE) WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE
+#define COMPILER_SUPPORTS(WTF_COMPILER_FEATURE) (defined WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE && WTF_COMPILER_SUPPORTS_##WTF_COMPILER_FEATURE)
 
 /* COMPILER_QUIRK() - whether the compiler being used to build the project requires a given quirk. */
-#define COMPILER_QUIRK(WTF_COMPILER_QUIRK) WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK
+#define COMPILER_QUIRK(WTF_COMPILER_QUIRK) (defined WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK && WTF_COMPILER_QUIRK_##WTF_COMPILER_QUIRK)
 
 /* ==== COMPILER() - the compiler being used to build the project ==== */
 
diff --git a/src/3rdparty/masm/wtf/Platform.h b/src/3rdparty/masm/wtf/Platform.h
index 4146879c5a..fb2bb447d7 100644
--- a/src/3rdparty/masm/wtf/Platform.h
+++ b/src/3rdparty/masm/wtf/Platform.h
@@ -39,7 +39,7 @@
 /* ==== PLATFORM handles OS, operating environment, graphics API, and
    CPU. This macro will be phased out in favor of platform adaptation
    macros, policy decision macros, and top-level port definitions. ==== */
-#define PLATFORM(WTF_FEATURE) WTF_PLATFORM_##WTF_FEATURE
+#define PLATFORM(WTF_FEATURE) (defined WTF_PLATFORM_##WTF_FEATURE && WTF_PLATFORM_##WTF_FEATURE)
 
 
 /* ==== Platform adaptation macros: these describe properties of the target environment. ==== */
@@ -48,20 +48,20 @@
 #ifdef Q_OS_VXWORKS
 #undef CPU
 #endif // Q_OS_VXWORKS
-#define CPU(WTF_FEATURE) WTF_CPU_##WTF_FEATURE
+#define CPU(WTF_FEATURE) (defined WTF_CPU_##WTF_FEATURE && WTF_CPU_##WTF_FEATURE)
 /* HAVE() - specific system features (headers, functions or similar) that are present or not */
-#define HAVE(WTF_FEATURE) HAVE_##WTF_FEATURE
+#define HAVE(WTF_FEATURE) (defined HAVE_##WTF_FEATURE && HAVE_##WTF_FEATURE)
 /* OS() - underlying operating system; only to be used for mandated low-level services like 
    virtual memory, not to choose a GUI toolkit */
-#define OS(WTF_FEATURE) WTF_OS_##WTF_FEATURE
+#define OS(WTF_FEATURE) (defined WTF_OS_##WTF_FEATURE && WTF_OS_##WTF_FEATURE)
 
 
 /* ==== Policy decision macros: these define policy choices for a particular port. ==== */
 
 /* USE() - use a particular third-party library or optional OS service */
-#define USE(WTF_FEATURE) WTF_USE_##WTF_FEATURE
+#define USE(WTF_FEATURE) (defined WTF_USE_##WTF_FEATURE && WTF_USE_##WTF_FEATURE)
 /* ENABLE() - turn on a specific feature of WebKit */
-#define ENABLE(WTF_FEATURE) ENABLE_##WTF_FEATURE
+#define ENABLE(WTF_FEATURE) (defined ENABLE_##WTF_FEATURE && ENABLE_##WTF_FEATURE)
 
 
 /* ==== CPU() - the target CPU architecture ==== */