diff --git a/build.sh b/build.sh
index d8fd486..4e1f21f 100644
--- a/build.sh
+++ b/build.sh
@@ -18,7 +18,7 @@ output="out/why2"
 flags="-ljson-c -lcurl"
 
 # Check for debug flag
-if [ "$1" == "debug" ]; then
+if [[ "$1" == "debug" ]]; then
     flags="$flags -g"
     echo "Using debug flag"
 fi