diff --git a/include/SDL_config_os2.h b/include/SDL_config_os2.h
index 16a690bf7..63d288060 100644
--- a/include/SDL_config_os2.h
+++ b/include/SDL_config_os2.h
@@ -180,7 +180,7 @@
 /* #undef HAVE_SQRTF */
 #define HAVE_TAN 1
 /* #undef HAVE_TANF */
-#define HAVE_TRUNC 1
+/* #undef HAVE_TRUNC */
 /* #undef HAVE_TRUNCF */
 
 #endif /* SDL_config_os2_h_ */