diff --git a/Formula/ssreflect.rb b/Formula/ssreflect.rb
index 2844dbf65f..f246bac574 100644
--- a/Formula/ssreflect.rb
+++ b/Formula/ssreflect.rb
@@ -41,6 +41,8 @@ class Ssreflect < Formula
   patch :DATA
 
   def install
+    ENV["OCAMLPARAM"] = "safe-string=0,_" # OCaml 4.06.0 compat
+
     resource("coq84").stage do
       system "./configure", "-prefix", libexec/"coq",
                             "-camlp5dir", Formula["camlp5"].opt_lib/"ocaml/camlp5",