diff --git a/m4/ax_mexext.m4 b/m4/ax_mexext.m4
index 569a9c9a7395373dc26308a0e55548f47f0d47c5..208a0b18458f238e42de60143e9d0f39f63ef12b 100644
--- a/m4/ax_mexext.m4
+++ b/m4/ax_mexext.m4
@@ -46,7 +46,7 @@ else
         ax_cv_mexext=`$MATLAB/bin/mexext.bat | sed 's/\r//'`
         ;;
       *mingw*)
-        ax_cv_mexext=`cd $MATLAB && cmd /c mexext.bat | sed 's/\r//'`
+        ax_cv_mexext=`cd $MATLAB/bin && cmd /c mexext.bat | sed 's/\r//'`
         ;;
       *)
         ax_cv_mexext=`$MATLAB/bin/mexext`