diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4a61056b49..f89be5a1b7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3456,7 +3456,7 @@ if(APPLE)
 endif()
 
 if(PLAYDATE)
-  target_include_directories(sdl-build-options INTERFACE "${SDK}/C_API")
+  target_include_directories(sdl-build-options INTERFACE "${PLAYDATE_SDK_PATH}/C_API")
 endif()
 
 if(SDL_SHARED)