diff --git a/lib/linguist/heuristics.rb b/lib/linguist/heuristics.rb
index ad65bafb..007f5622 100644
--- a/lib/linguist/heuristics.rb
+++ b/lib/linguist/heuristics.rb
@@ -33,9 +33,10 @@ module Linguist
       matches
     end
 
-    def self_disambiguate_pl(data, languages)
+    def self.disambiguate_pl(data, languages)
       matches = []
       matches << Language["Prolog"] if data.include?(":-")
+      matches << Language["Perl"] if data.include?("use strict")
       matches
     end
 
diff --git a/test/test_heuristics.rb b/test/test_heuristics.rb
index 5a036f1f..a7847173 100644
--- a/test/test_heuristics.rb
+++ b/test/test_heuristics.rb
@@ -38,4 +38,16 @@ class TestHeuristcs < Test::Unit::TestCase
     match = Language.detect("Hello.m", fixture("Objective-C/hello.m"))
     assert_equal Language["Objective-C"], match
   end
+  
+  def test_pl_prolog_by_heuristics
+    languages = ["Perl", "Prolog"]
+    results = Heuristics.disambiguate_pl(fixture("Prolog/turing.pl"), languages)
+    assert_equal Language["Prolog"], results.first
+  end
+  
+  def test_pl_perl_by_heuristics
+    languages = ["Perl", "Prolog"]
+    results = Heuristics.disambiguate_pl(fixture("Perl/perl-test.t"), languages)
+    assert_equal Language["Perl"], results.first
+  end
 end