diff --git a/src/posix/cocoa/i_main.mm b/src/posix/cocoa/i_main.mm
index 665f2203a6..e6cf65d4ac 100644
--- a/src/posix/cocoa/i_main.mm
+++ b/src/posix/cocoa/i_main.mm
@@ -63,6 +63,10 @@ EXTERN_CVAR(Int,  vid_defheight)
 EXTERN_CVAR(Bool, vid_vsync    )
 EXTERN_CVAR(Bool, fullscreen   )
 
+CVAR(Bool, vr_enable_quadbuffered, false, CVAR_NOSET)
+/* this is to fix compile on non-Windows platforms because this code is only
+   used on Windows, anyhow, but references to it exist elsewhere in the code */
+
 
 // ---------------------------------------------------------------------------
 
diff --git a/src/posix/sdl/sdlglvideo.cpp b/src/posix/sdl/sdlglvideo.cpp
index 98c8dcab49..39dfd6e4d2 100644
--- a/src/posix/sdl/sdlglvideo.cpp
+++ b/src/posix/sdl/sdlglvideo.cpp
@@ -72,6 +72,12 @@ EXTERN_CVAR (Bool, cl_capfps)
 
 DFrameBuffer *CreateGLSWFrameBuffer(int width, int height, bool bgra, bool fullscreen);
 
+// DUMMY DATA DEFINITIONS --------------------------------------------------
+
+CVAR(Bool, vr_enable_quadbuffered, false, CVAR_NOSET)
+/* this is to fix compile on non-Windows platforms because this code is only
+   used on Windows, anyhow, but references to it exist elsewhere in the code */
+
 // PUBLIC DATA DEFINITIONS -------------------------------------------------
 
 CUSTOM_CVAR(Bool, gl_debug, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG | CVAR_NOINITCALL)