diff --git a/deny.toml b/deny.toml
index adf78900..3720748e 100644
--- a/deny.toml
+++ b/deny.toml
@@ -51,7 +51,8 @@ allow = [
     "Unicode-DFS-2016",
     "Unicode-3.0",
     "BSD-3-Clause",
-    "MPL-2.0"
+    "MPL-2.0",
+    "Zlib",
 ]
 # The confidence threshold for detecting a license from license text.
 confidence-threshold = 0.8