diff --git a/flow/BUILD.gn b/flow/BUILD.gn
index 5cbefb0113710be60400d5db7ea51fb0c9d97af9..6f6b7e2a0db6774277bdb6d0ef36b66b205c96ce 100644
--- a/flow/BUILD.gn
+++ b/flow/BUILD.gn
@@ -77,7 +77,7 @@ source_set("flow") {
       "//garnet/public/lib/fidl/dart/sdk_ext",
     ]
 
-    public_deps = [
+    public_deps += [
       "//magenta/system/ulib/mx",
     ]
   }