diff --git a/bb.sh b/bb.sh
index 24353f5..3125ecf 100755
--- a/bb.sh
+++ b/bb.sh
@@ -178,6 +178,7 @@ global_variables() {
 # Test if the markdown script is working correctly
 test_markdown() {
     [[ -z "$markdown_bin" ]] && return 1
+    [[ -z "$(which diff)" ]] && return 1
 
     in="/tmp/md-in-$(echo $RANDOM).md"
     out="/tmp/md-out-$(echo $RANDOM).html"