diff --git a/lib/linguist/heuristics.rb b/lib/linguist/heuristics.rb
index 7e343d58..ad65bafb 100644
--- a/lib/linguist/heuristics.rb
+++ b/lib/linguist/heuristics.rb
@@ -14,7 +14,10 @@ module Linguist
     def self.find_by_heuristics(data, languages)
       if active?
         if languages.all? { |l| ["Objective-C", "C++"].include?(l) }
-          disambiguate_h(data, languages)
+          disambiguate_c(data, languages)
+        end
+        if languages.all? { |l| ["Perl", "Prolog"].include?(l) }
+          disambiguate_pl(data, languages)
         end
       end
     end
@@ -23,14 +26,19 @@ module Linguist
     # We want to shortcut look for Objective-C _and_ now C++ too!
     #
     # Returns an array of Languages or []
-    # TODO rename this method as we're not strictly disambiguating between .h files here.
-    def self.disambiguate_h(data, languages)
+    def self.disambiguate_c(data, languages)
       matches = []
       matches << Language["Objective-C"] if data.include?("@interface")
       matches << Language["C++"] if data.include?("#include <cstdint>")
       matches
     end
 
+    def self_disambiguate_pl(data, languages)
+      matches = []
+      matches << Language["Prolog"] if data.include?(":-")
+      matches
+    end
+
     def self.active?
       !!ACTIVE
     end
diff --git a/test/test_heuristics.rb b/test/test_heuristics.rb
index 6a5a748c..5a036f1f 100644
--- a/test/test_heuristics.rb
+++ b/test/test_heuristics.rb
@@ -23,14 +23,14 @@ class TestHeuristcs < Test::Unit::TestCase
   def test_obj_c_by_heuristics
     languages = ["C++", "Objective-C"]
     all_h_fixtures("Objective-C").each do |fixture|
-      results = Heuristics.disambiguate_h(fixture("Objective-C/#{File.basename(fixture)}"), languages)
+      results = Heuristics.disambiguate_c(fixture("Objective-C/#{File.basename(fixture)}"), languages)
       assert_equal Language["Objective-C"], results.first
     end
   end
-   
+
   def test_cpp_by_heuristics
     languages = ["C++", "Objective-C"]
-    results = Heuristics.disambiguate_h(fixture("C++/render_adapter.cpp"), languages)
+    results = Heuristics.disambiguate_c(fixture("C++/render_adapter.cpp"), languages)
     assert_equal Language["C++"], results.first
   end