diff --git a/src/monger/conversion.clj b/src/monger/conversion.clj
index 23ca31b..76f41bb 100644
--- a/src/monger/conversion.clj
+++ b/src/monger/conversion.clj
@@ -23,7 +23,7 @@
 
 (ns monger.conversion
   (:import [com.mongodb DBObject BasicDBObject BasicDBList DBCursor]
-           [clojure.lang IPersistentMap Keyword]
+           [clojure.lang IPersistentMap Keyword Ratio]
            [java.util List Map Date]
            [org.bson.types ObjectId]))
 
@@ -39,6 +39,10 @@
   (to-db-object [input]
     input)
 
+  Ratio
+  (to-db-object [^Ratio input]
+    (double input))
+
   Keyword
   (to-db-object [^Keyword input] (.getName input))
 
diff --git a/test/monger/test/conversion.clj b/test/monger/test/conversion.clj
index 2d15643..dfa960e 100644
--- a/test/monger/test/conversion.clj
+++ b/test/monger/test/conversion.clj
@@ -26,6 +26,11 @@
         output (cnv/to-db-object input)]
     (is (= input output))))
 
+(deftest convert-rationale-to-dbobject
+  (let [input  11/2
+        output (cnv/to-db-object input)]
+    (is (= 5.5 output))))
+
 (deftest convert-string-to-dbobject
   (let [input  "MongoDB"
         output (cnv/to-db-object input)]
diff --git a/test/monger/test/inserting.clj b/test/monger/test/inserting.clj
index 366e97e..7924451 100644
--- a/test/monger/test/inserting.clj
+++ b/test/monger/test/inserting.clj
@@ -55,6 +55,13 @@
         result     (mgcol/insert "people" doc)]
     (is (= id (monger.util/get-id doc)))))
 
+(deftest insert-a-document-with-clojure-ratio-in-it
+  (let [collection "widgets"
+        id         (ObjectId.)
+        doc        { :ratio 11/2 "_id" id }
+        result     (mgcol/insert "widgets" doc)]
+    (is (= 5.5 (:ratio (mgcol/find-map-by-id collection id))))))
+
 
 
 ;;