diff --git a/check b/check
index 2d07ed50..40f5d0a3 100755
--- a/check
+++ b/check
@@ -150,7 +150,7 @@ echo "preamble" >/tmp/check.sts
 rm -f check.full
 
 # by default don't output timestamps
-timestamp=false
+timestamp=${TIMESTAMP:=false}
 
 . ./common