diff --git a/lib/linguist/heuristics.rb b/lib/linguist/heuristics.rb
index e38b7475..97808975 100644
--- a/lib/linguist/heuristics.rb
+++ b/lib/linguist/heuristics.rb
@@ -187,6 +187,12 @@ module Linguist
       end
     end
 
+    disambiguate ".inc" do |data|
+      if /^<\?(?:php)?/.match(data)
+        Language["PHP"]
+      end
+    end
+
     disambiguate ".l" do |data|
       if /\(def(un|macro)\s/.match(data)
         Language["Common Lisp"]
diff --git a/test/test_heuristics.rb b/test/test_heuristics.rb
index e022ce6b..f73ef7b8 100644
--- a/test/test_heuristics.rb
+++ b/test/test_heuristics.rb
@@ -122,6 +122,12 @@ class TestHeuristcs < Minitest::Test
     })
   end
 
+  def test_inc_by_heuristics
+    assert_heuristics({
+      "PHP" => all_fixtures("PHP", "*.inc")
+    })
+  end
+
   def test_ls_by_heuristics
     assert_heuristics({
       "LiveScript" => all_fixtures("LiveScript", "*.ls"),