diff --git a/tools/examples/block b/tools/examples/block
index 1cf6fb8fc8..411e6813fe 100644
--- a/tools/examples/block
+++ b/tools/examples/block
@@ -322,6 +322,7 @@ mount it read-write in a guest domain."
 
         if [ "$loopdev" = '' ]
         then
+          release_lock "block"
           fatal 'Failed to find an unused loop device'
         fi