--- a/configure.ac
+++ b/configure.ac
@@ -1265,7 +1265,7 @@
 	if test "x$with_optim" != x; then
 	    OPTIM="$with_optim $OPTIM"
 	else
-	    OPTIM="-Os $OPTIM"
+	    OPTIM=" $OPTIM"
 	fi
     fi
 
