diff --git a/slides/build.sh b/slides/build.sh
index de646a8d..3515ebbb 100755
--- a/slides/build.sh
+++ b/slides/build.sh
@@ -7,9 +7,11 @@ once)
       break
     }
   done
-  [ -n "$SLIDECHECKER" ] && for YAML in *.yml; do
-    ./appendcheck.py $YAML.html
-  done
+  if [ -n "$SLIDECHECKER" ]; then
+    for YAML in *.yml; do
+      ./appendcheck.py $YAML.html
+    done
+  fi
   ;;
 
 forever)