diff --git a/configure.ac b/configure.ac
index 1563876..5c753c0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1593,6 +1593,7 @@
 AC_SUBST(LDPATH,"")
 case $build_os in
   cygwin*|mingw32*)
+    AC_SUBST(TOOLSEXT,".exe")
     LDPATH="PATH=\"\$(TOOLSDIR)/libs/wine:\$\$PATH\""
     ;;
   darwin*|macosx*)