diff --git a/lib/mock_redis/zset.rb b/lib/mock_redis/zset.rb
index 736e3a5..d18fbcf 100644
--- a/lib/mock_redis/zset.rb
+++ b/lib/mock_redis/zset.rb
@@ -23,12 +23,7 @@ def initialize_copy(source)
 
     def add(score, member)
       members.add(member)
-      scores[member] =
-        if score.to_f.to_i == score.to_f
-          score.to_f.to_i
-        else
-          score.to_f
-        end
+      scores[member] = score.to_f
       self
     end
 
diff --git a/spec/commands/zadd_spec.rb b/spec/commands/zadd_spec.rb
index a2afcc6..a3f3242 100644
--- a/spec/commands/zadd_spec.rb
+++ b/spec/commands/zadd_spec.rb
@@ -23,6 +23,12 @@
     @redises.zrange(@key, 0, -1).should == [member.to_s]
   end
 
+  it 'allows scores to be set to Float::INFINITY' do
+    member = '1'
+    @redises.zadd(@key, Float::INFINITY, member)
+    @redises.zrange(@key, 0, -1).should == [member]
+  end
+
   it 'updates the score' do
     @redises.zadd(@key, 1, 'foo')
     @redises.zadd(@key, 2, 'foo')