diff --git a/check_nmap.sh b/check_nmap.sh
index b4e1fff..2a7ff6e 100755
--- a/check_nmap.sh
+++ b/check_nmap.sh
@@ -47,6 +47,11 @@ if [ -z "$HOST" -a -z "$INPUT" ]; then
 	exit 3
 fi
 
+if ! command -v nmap &> /dev/null; then
+	echoerr "Missing nmap executable"
+	exit 3
+fi
+
 function log {
 	if $DEBUG; then
 		echo "  > $@"