diff --git a/src/freedombone-base-tripwire b/src/freedombone-base-tripwire
index 2c0db7eb..74772c79 100755
--- a/src/freedombone-base-tripwire
+++ b/src/freedombone-base-tripwire
@@ -139,9 +139,11 @@ function install_tripwire {
 
        ' | reset-tripwire
 
-    TRIPWIRE_MIN=$((1 + RANDOM % 49))
-    TRIPWIRE_HOUR=$((1 + RANDOM % 6))
-    echo "${TRIPWIRE_MIN} ${TRIPWIRE_HOUR}              *   *   *   root /usr/sbin/tripwire -m c" /etc/crontab
+    if ! grep -q "tripwire" /etc/crontab; then
+        TRIPWIRE_MIN=$((1 + RANDOM % 49))
+        TRIPWIRE_HOUR=$((1 + RANDOM % 6))
+        echo "${TRIPWIRE_MIN} ${TRIPWIRE_HOUR}              *   *   *   root /usr/sbin/tripwire -m c" >> /etc/crontab
+    fi
 
     mark_completed $FUNCNAME
 }