diff --git a/mex/build/matlab/configure.ac b/mex/build/matlab/configure.ac
index 4132f54b5cfd4408e09dcf8f24d25258a3f97290..16653cae75d6e849e18564a2978c4784ddab1fc7 100644
--- a/mex/build/matlab/configure.ac
+++ b/mex/build/matlab/configure.ac
@@ -50,6 +50,9 @@ case ${host_os} in
     ;;
 esac
 
+CFLAGS="$CFLAGS -Wall"
+CXXFLAGS="$CXXFLAGS -Wall"
+
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_RANLIB
diff --git a/mex/build/octave/configure.ac b/mex/build/octave/configure.ac
index 9a4f74a75c30b553cf8caf649d348ca99ad34e83..4fd07818a3a388a5447a65910977191c90abe14e 100644
--- a/mex/build/octave/configure.ac
+++ b/mex/build/octave/configure.ac
@@ -31,6 +31,9 @@ if test "x$MKOCTFILE" != "x"; then
   CXXFLAGS=`$MKOCTFILE -p CXXFLAGS`
 fi
 
+CFLAGS="$CFLAGS -Wall"
+CXXFLAGS="$CXXFLAGS -Wall"
+
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_RANLIB