diff --git a/.travis.yml b/.travis.yml
index f6683368..3e01acbc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,7 +44,7 @@ script:
   - |
     for example in $(find $PWD/examples -name '*.ino' | sort); do
       # check whether to skip this sketch
-      if [[ ${example} =~ $SKIP_PAT ]]; then
+      if [ ! -z "$SKIP_PAT" ] && [[ ${example} =~ $SKIP_PAT ]]; then
         # skip sketch
         echo -e "\n\033[1;33mSkipped ${example##*/} (matched with $SKIP_PAT)\033[0m";
       else