diff --git a/panda/src/display/CMakeLists.txt b/panda/src/display/CMakeLists.txt
index 106fab5646..583b60f79e 100644
--- a/panda/src/display/CMakeLists.txt
+++ b/panda/src/display/CMakeLists.txt
@@ -78,12 +78,17 @@ if(HAVE_PYTHON)
 	)
 endif()
 
-if(OSX_PLATFORM)
-	set(P3DISPLAY_HEADER
+if(APPLE)
+	set(P3DISPLAY_HEADERS
 		${P3DISPLAY_HEADERS}
 		subprocessWindowBuffer.h
 		subprocessWindowBuffer.I
 	)
+
+	set(P3DISPLAY_SOURCES
+		${P3DISPLAY_SOURCES}
+		subprocessWindowBuffer.cxx
+	)
 endif()
 
 composite_sources(p3display P3DISPLAY_SOURCES)