diff --git a/lib/simplecov/file_list.rb b/lib/simplecov/file_list.rb
index 21b3d75c..d5b9609c 100644
--- a/lib/simplecov/file_list.rb
+++ b/lib/simplecov/file_list.rb
@@ -31,14 +31,16 @@ def lines_of_code
   end
 
   # Computes the coverage based upon lines covered and lines missed
+  # @return [Float]
   def covered_percent
     return 100.0 if empty? or lines_of_code == 0
-    covered_lines * 100.0 / lines_of_code
+    Float(covered_lines * 100.0 / lines_of_code)
   end
 
   # Computes the strength (hits / line) based upon lines covered and lines missed
+  # @return [Float]
   def covered_strength
-    return 0 if empty? or lines_of_code == 0
-    map {|f| f.covered_strength }.inject(&:+).to_f / size
+    return 0.0 if empty? or lines_of_code == 0
+    Float(map {|f| f.covered_strength }.inject(&:+).to_f / size)
   end
 end
diff --git a/lib/simplecov/result.rb b/lib/simplecov/result.rb
index 55268100..4f1a36de 100644
--- a/lib/simplecov/result.rb
+++ b/lib/simplecov/result.rb
@@ -47,7 +47,7 @@ def groups
     # The overall percentual coverage for this result
     def covered_percent
       # Make sure that weird rounding error from #15, #23 and #24 does not occur again!
-      total_lines.zero? ? 0 : 100.0 * covered_lines / total_lines
+      total_lines.zero? ? 0 : Float(100.0 * covered_lines / total_lines)
     end
 
     # The multiple of coverage for this result
@@ -62,7 +62,7 @@ def covered_strength
           end
         end
       end
-      @covered_strength = m.to_f / total_lines
+      @covered_strength = Float(m.to_f / total_lines)
     end
 
     # Returns the count of lines that are covered
diff --git a/lib/simplecov/source_file.rb b/lib/simplecov/source_file.rb
index 9e578098..e091e2a7 100644
--- a/lib/simplecov/source_file.rb
+++ b/lib/simplecov/source_file.rb
@@ -111,24 +111,24 @@ def covered_percent
       return 100.0 if lines.length == 0 or lines.length == never_lines.count
       relevant_lines = lines.count - never_lines.count - skipped_lines.count
       if relevant_lines == 0
-        0
+        0.0
       else
-        (covered_lines.count) * 100.0 / relevant_lines.to_f
+        Float((covered_lines.count) * 100.0 / relevant_lines.to_f)
       end
     end
 
     def covered_strength
-      return 0 if lines.length == 0 or lines.length == never_lines.count
+      return 0.0 if lines.length == 0 or lines.length == never_lines.count
 
       lines_strength = 0
       lines.each do |c|
         lines_strength += c.coverage if c.coverage
       end
 
-      effective_lines_count = (lines.count - never_lines.count - skipped_lines.count).to_f
+      effective_lines_count = Float(lines.count - never_lines.count - skipped_lines.count)
 
       if effective_lines_count == 0
-        0
+        0.0
       else
         strength = lines_strength / effective_lines_count
         round_float(strength, 1)
@@ -178,9 +178,10 @@ def process_skipped_lines!
     private
 
     # ruby 1.9 could use Float#round(places) instead
+    # @return [Float]
     def round_float(float, places)
-      factor = (10 * places).to_f
-      (float * factor).round / factor
+      factor = Float(10 * places)
+      Float((float * factor).round / factor)
     end
   end
 end