diff --git a/lib/linguist/heuristics.rb b/lib/linguist/heuristics.rb
index <HASH>..<HASH> 100644
--- a/lib/linguist/heuristics.rb
+++ b/lib/linguist/heuristics.rb
@@ -355,7 +355,7 @@ module Linguist
     disambiguate ".php" do |data|
       if data.include?("<?hh")
         Language["Hack"]
-      elsif /<?[^h]/.match(data)
+      elsif /<\?[^h]/.match(data)
         Language["PHP"]
       end
     end
fix php disambiguation regex (#<I>)

Because of an error in the regular expression, disambiguation rule for the .php

matched any non-empty file as PHP, except for Hack files.