diff --git a/http/misconfiguration/proxy/open-proxy-external.yaml b/http/misconfiguration/proxy/open-proxy-external.yaml
index 5817b5c8d6..6a6c494ee1 100644
--- a/http/misconfiguration/proxy/open-proxy-external.yaml
+++ b/http/misconfiguration/proxy/open-proxy-external.yaml
@@ -43,5 +43,5 @@ http:
       - type: dsl
         dsl:
           - '!contains(body_3, "<HostId>")'
-          - !contains(header_3, "X-Interactsh-Version")
+          - '!contains(header_3, "X-Interactsh-Version")'
         condition: and