diff --git a/spec/openapi.yaml b/spec/openapi.yaml
index ea9c105..7dc7d92 100644
--- a/spec/openapi.yaml
+++ b/spec/openapi.yaml
@@ -142,7 +142,7 @@ tags:
 
       ```plain
 
-      Date: Sat, 30 Jul 2016 05:13:23 GMT\nContent-MD5:10fd4feab20d38432480c07301e49616\nPOST /v1/messages HTTP/1.1
+      Date: Sat, 30 Jul 2016 05:13:23 GMT\nContent-MD5: 10fd4feab20d38432480c07301e49616\nPOST /v1/messages HTTP/1.1
 
       ```