diff --git a/tests/compat.sh b/tests/compat.sh
index 67a6f5f2b..28c8021f6 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -954,9 +954,6 @@ for PEER in $PEERS; do
     esac
 done
 
-# used by watchdog
-MAIN_PID="$$"
-
 # Pick a "unique" port in the range 10000-19999.
 PORT="0000$$"
 PORT="1$(echo $PORT | tail -c 5)"