diff --git a/Sources/Plasma/CoreLib/HeadSpin.h b/Sources/Plasma/CoreLib/HeadSpin.h
index 41985112..76a98e8d 100644
--- a/Sources/Plasma/CoreLib/HeadSpin.h
+++ b/Sources/Plasma/CoreLib/HeadSpin.h
@@ -45,9 +45,9 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 // Ensure these get set consistently regardless of what module includes it
 #include "hsCompilerSpecific.h"
 
-#if (defined(_DEBUG) || defined(UNIX_DEBUG))
+#if defined(_DEBUG)
 #   define HS_DEBUGGING
-#endif // defined(_DEBUG) || defined(UNIX_DENUG)
+#endif
 
 //======================================
 // Some standard includes
diff --git a/cmake/CompilerChecks.cmake b/cmake/CompilerChecks.cmake
index aa85866c..973b671c 100644
--- a/cmake/CompilerChecks.cmake
+++ b/cmake/CompilerChecks.cmake
@@ -11,6 +11,13 @@ if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANGXX)
     endif()
 endif()
 
+# MSVC automatically defines -D_DEBUG when /MTd or /MDd is set, so we
+# need to make sure it gets added for other compilers too
+if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANGXX)
+    set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG")
+    set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -D_DEBUG")
+endif()
+
 
 # Compile-time type size checks
 include(CheckTypeSize)