diff --git a/scripts/bump.sh b/scripts/bump.sh
index d0e0765..445622e 100755
--- a/scripts/bump.sh
+++ b/scripts/bump.sh
@@ -7,7 +7,7 @@ fi
 
 VERSION=$1
 
-if echo $VERSION | grep "^[0-9.]"; then
+if ! echo $VERSION | grep "^[0-9.]"; then
     echo "invalid version";
     exit 1
 fi