diff --git a/NTMakefile b/NTMakefile
index 00c5a54f0..9848a7897 100644
--- a/NTMakefile
+++ b/NTMakefile
@@ -29,7 +29,7 @@
 # POSSIBILITY OF SUCH DAMAGE.
 #
 
-!if exist(thirdparty/NTMakefile)
+!if exist("thirdparty\NTMakefile")
 thirdparty=thirdparty
 !endif