diff --git a/tasks/build.rake b/tasks/build.rake
index 8aeace965..d8aa52a64 100644
--- a/tasks/build.rake
+++ b/tasks/build.rake
@@ -54,7 +54,7 @@ def image_exists
 end
 
 def container_exists
-  !`docker container ls --all --filter 'name=#{@container}' --format json`.strip.empty?
+  !`docker container ls --all --filter 'name=#{@container}' --format '{{json .ID}}'`.strip.empty?
 end
 
 def teardown