diff --git a/mex/build/matlab/configure.ac b/mex/build/matlab/configure.ac
index 0b854aa09..6550f8e16 100644
--- a/mex/build/matlab/configure.ac
+++ b/mex/build/matlab/configure.ac
@@ -46,7 +46,7 @@ case ${host_os} in
     CC=gcc-3
     CXX=g++-3
     CFLAGS="$CFLAGS -mno-cygwin"
-    CXXFLAGS="$CFLAGS -mno-cygwin"
+    CXXFLAGS="$CXXFLAGS -mno-cygwin"
     ;;
 esac