diff --git a/lib/simplecov.rb b/lib/simplecov.rb
index 5a47df30..c490bdd2 100644
--- a/lib/simplecov.rb
+++ b/lib/simplecov.rb
@@ -321,7 +321,7 @@ def add_not_loaded_files(result)
         result = result.dup
         Dir[tracked_files].each do |file|
           absolute_path = File.expand_path(file)
-          result[absolute_path] ||= SimulateCoverage.call(absolute_path)
+          result[absolute_path.to_sym] ||= SimulateCoverage.call(absolute_path)
         end
       end
 
diff --git a/lib/simplecov/result.rb b/lib/simplecov/result.rb
index f79cfb19..dc9e386e 100644
--- a/lib/simplecov/result.rb
+++ b/lib/simplecov/result.rb
@@ -80,7 +80,7 @@ def self.from_hash(hash)
   private
 
     def coverage
-      keys = original_result.keys & filenames
+      keys = original_result.keys & filenames.map(&:to_sym)
       Hash[keys.zip(original_result.values_at(*keys))]
     end
 
diff --git a/lib/simplecov/result_adapter.rb b/lib/simplecov/result_adapter.rb
index 79cf8e6f..996c8d31 100644
--- a/lib/simplecov/result_adapter.rb
+++ b/lib/simplecov/result_adapter.rb
@@ -20,9 +20,9 @@ def adapt
 
       result.each_with_object({}) do |(file_name, cover_statistic), adapted_result|
         if cover_statistic.is_a?(Array)
-          adapted_result.merge!(file_name => {lines: cover_statistic})
+          adapted_result.merge!(file_name.to_sym => {lines: cover_statistic})
         else
-          adapted_result.merge!(file_name => cover_statistic)
+          adapted_result.merge!(file_name.to_sym => cover_statistic)
         end
       end
     end
diff --git a/spec/helper.rb b/spec/helper.rb
index 44fbf0f4..e747a5eb 100644
--- a/spec/helper.rb
+++ b/spec/helper.rb
@@ -10,7 +10,7 @@
 SimpleCov.coverage_dir("tmp/coverage")
 
 def source_fixture(filename)
-  File.expand_path(File.join(File.dirname(__FILE__), "fixtures", filename))
+  File.expand_path(File.join(File.dirname(__FILE__), "fixtures", filename)).to_sym
 end
 
 # Taken from http://stackoverflow.com/questions/4459330/how-do-i-temporarily-redirect-stderr-in-ruby