diff --git a/project.clj b/project.clj
index bdb648d..3da2d55 100644
--- a/project.clj
+++ b/project.clj
@@ -1,8 +1,7 @@
 (defproject dk.ative/docjure "1.6.0-SNAPSHOT"
   :description "Easily read and write Office documents from Clojure."
   :url "http://github.com/ative/docjure"
-  :dependencies [[org.clojure/clojure "1.2.0"]
-                 [org.clojure/clojure-contrib "1.2.0"]
+  :dependencies [[org.clojure/clojure "1.3.0"]
 		 [org.apache.poi/poi "3.6"]
 		 [org.apache.poi/poi-ooxml "3.6"]]
   :dev-dependencies [[swank-clojure "1.3.0-SNAPSHOT"]
diff --git a/src/dk/ative/docjure/spreadsheet.clj b/src/dk/ative/docjure/spreadsheet.clj
index 3338d06..e2dd8c1 100644
--- a/src/dk/ative/docjure/spreadsheet.clj
+++ b/src/dk/ative/docjure/spreadsheet.clj
@@ -29,7 +29,7 @@
 	   (let [evaluator (.. cell getSheet getWorkbook
 			       getCreationHelper createFormulaEvaluator)
 		 cv (.evaluate evaluator cell)]
-	     (read-cell-value cv (DateUtil/isCellDateFormatted cell))))
+	     (read-cell-value cv false)))
 (defmethod read-cell Cell/CELL_TYPE_BOOLEAN   [cell]  (.getBooleanCellValue cell))
 (defmethod read-cell Cell/CELL_TYPE_NUMERIC   [cell]
   (if (DateUtil/isCellDateFormatted cell)
@@ -44,27 +44,27 @@
 
 (defn save-workbook! 
   "Save the workbook into a file."
-  [filename #^Workbook workbook]
+  [filename ^Workbook workbook]
   (assert-type workbook Workbook)
   (with-open [file-out (FileOutputStream. filename)]
     (.write workbook file-out)))
 
 (defn sheet-seq 
   "Return a lazy seq of the sheets in a workbook."
-  [#^Workbook workbook]
+  [^Workbook workbook]
   (assert-type workbook Workbook)
   (for [idx (range (.getNumberOfSheets workbook))]
     (.getSheetAt workbook idx)))
 
 (defn sheet-name
   "Return the name of a sheet."
-  [#^Sheet sheet]
+  [^Sheet sheet]
   (assert-type sheet Sheet)
   (.getSheetName sheet))
 
 (defn select-sheet 
   "Select a sheet from the workbook by name."
-  [name #^Workbook workbook]
+  [name ^Workbook workbook]
   (assert-type workbook Workbook)
   (->> (sheet-seq workbook)
        (filter #(= name (sheet-name %)))
@@ -72,7 +72,7 @@
 
 (defn row-seq 
   "Return a lazy sequence of the rows in a sheet."
-  [#^Sheet sheet]
+  [^Sheet sheet]
   (assert-type sheet Sheet)
   (iterator-seq (.iterator sheet)))
 
@@ -100,7 +100,7 @@
   [sheet-or-row]
   (vec (for [item (iterator-seq (.iterator sheet-or-row))] item)))
 
-(defn- project-cell [column-map #^Cell cell]
+(defn- project-cell [column-map ^Cell cell]
   (let [colname (-> cell
 		    .getColumnIndex 
 		    org.apache.poi.ss.util.CellReference/convertNumToColString
@@ -109,7 +109,7 @@
     (when new-key
       {new-key (read-cell cell)})))
 
-(defn select-columns [column-map #^Sheet sheet]
+(defn select-columns [column-map ^Sheet sheet]
   "Takes two arguments: column hashmap where the keys are the
    spreadsheet column names as keys and the values represent the names they are mapped to, 
    and a sheet.
@@ -139,14 +139,17 @@
 		    (.. format-helper createDataFormat (getFormat format)))
     (.setCellStyle cell date-style)))
 
-(defn set-cell! [cell value]
-  (let [converted-value (cond (number? value) (double value)
-                          true value)]
-    (.setCellValue cell converted-value)
-    (if (date-or-calendar? value)
-      (apply-date-format! cell "m/d/yy"))))
-
-(defn add-row! [#^Sheet sheet values]
+(defn set-cell! [^Cell cell value]
+  (if (nil? value)
+    (let [^String null nil]
+      (.setCellValue cell null)) ;do not call setCellValue(Date) with null
+    (let [converted-value (cond (number? value) (double value)
+                                true value)]
+      (.setCellValue cell converted-value)
+      (if (date-or-calendar? value)
+        (apply-date-format! cell "m/d/yy")))))
+
+(defn add-row! [^Sheet sheet values]
   (assert-type sheet Sheet)
   (let [row-num (if (= 0 (.getPhysicalNumberOfRows sheet)) 
 		  0 
@@ -156,7 +159,7 @@
       (set-cell! (.createCell row column-index) value))
     row))
 
-(defn add-rows! [#^Sheet sheet rows]
+(defn add-rows! [^Sheet sheet rows]
   "Add rows to the sheet. The rows is a sequence of row-data, where
    each row-data is a sequence of values for the columns in increasing
    order on that row."
@@ -166,7 +169,7 @@
 
 (defn add-sheet! 
   "Add a new sheet to the workbook."
-  [#^Workbook workbook name]
+  [^Workbook workbook name]
   (assert-type workbook Workbook)
   (.createSheet workbook name))
 
@@ -200,7 +203,7 @@
 
       (create-font! wb {:bold true})
    "
-  [#^Workbook workbook options]
+  [^Workbook workbook options]
   (let [defaults {:bold false}
 	cfg (merge defaults options)]
     (assert-type workbook Workbook)
@@ -225,9 +228,9 @@
 
    (create-cell-style! wb {:background :yellow})
   "
-  ([#^Workbook workbook] (create-cell-style! workbook {}))
+  ([^Workbook workbook] (create-cell-style! workbook {}))
   
-  ([#^Workbook workbook styles]
+  ([^Workbook workbook styles]
      (assert-type workbook Workbook)
      (let [cs (.createCellStyle workbook)
 	   {background :background, font-style :font} styles
@@ -245,7 +248,7 @@
   "Apply a style to a cell.
    See also: create-cell-style!.
   "
-  [#^Cell cell #^CellStyle style]
+  [^Cell cell ^CellStyle style]
   (assert-type cell Cell)
   (assert-type style CellStyle)
   (.setCellStyle cell style)
@@ -254,7 +257,7 @@
 (defn set-row-style!
   "Apply a style to all the cells in a row.
    Returns the row."
-  [#^Row row #^CellStyle style]
+  [^Row row ^CellStyle style]
   (assert-type row Row)
   (assert-type style CellStyle)
   (dorun (map #(.setCellStyle % style) (cell-seq row)))
diff --git a/test/dk/ative/docjure/spreadsheet_test.clj b/test/dk/ative/docjure/spreadsheet_test.clj
index d473a05..7ae955d 100644
--- a/test/dk/ative/docjure/spreadsheet_test.clj
+++ b/test/dk/ative/docjure/spreadsheet_test.clj
@@ -110,7 +110,7 @@
 
 (deftest read-cell-test
   (let [sheet-data [["Nil" "Blank" "Date" "String" "Number"]
- 		    [nil "" (july 1) "foo" 42]]
+ 		    [nil "" (july 1) "foo" 42.0]]
  	workbook (create-workbook "Sheet 1" sheet-data)
 	sheet (.getSheetAt workbook 0)
  	rows  (vec (iterator-seq (.iterator sheet)))
@@ -121,7 +121,7 @@
       (is (nil? (read-cell nil-cell)))
       (is (= "" (read-cell blank-cell)))
       (is (= (july 1) (read-cell date-cell)))
-      (is (= 42 (read-cell number-cell))))))
+      (is (= 42.0 (read-cell number-cell))))))
 
 
 (deftest sheet-seq-test
@@ -205,8 +205,8 @@
 
 (deftest select-columns-test
   (let [data     [["Name" "Quantity" "Price" "On Sale"] 
-		  ["foo" 1 42 true] 
-		  ["bar" 2 108 false]]
+		  ["foo" 1.0 42 true] 
+		  ["bar" 2.0 108 false]]
 	workbook (create-workbook "Sheet 1" data)
 	sheet    (first (sheet-seq workbook))]
     (testing "Find existing columns should create map."