diff --git a/src/loiste/core.clj b/src/loiste/core.clj
index 9fa723c..26881b1 100644
--- a/src/loiste/core.clj
+++ b/src/loiste/core.clj
@@ -165,7 +165,9 @@
   (-write [value ^Cell cell options]
     (if (:style value)
       (.setCellStyle cell (get-in options [:styles (:style value)])))
-    (-write (:value value) cell options))
+    (-write (:value value) cell options)
+    (when-let [f (:build value)]
+      (f cell)))
   nil
   (-write [value ^Cell cell options]
     (.setBlank cell)))
@@ -183,11 +185,12 @@
          data
          (concat (:columns options) (repeat nil)))))
 
-(defn font [^Workbook wb {:keys [color name bold]}]
+(defn font [^Workbook wb {:keys [color name bold build]}]
   (doto (.createFont wb)
     (cond-> color (.setColor color))
     (cond-> name (.setFontName name))
-    (cond-> bold (.setBold bold))))
+    (cond-> bold (.setBold bold))
+    (cond-> build build)))
 
 (defn color [r g b]
   (XSSFColor. (byte-array 3 [(unchecked-byte r)
@@ -203,17 +206,24 @@
     :custom (let [^DataFormat data-fmt (.createDataFormat wb)]
               (.getFormat data-fmt ^String (:format-str data-format)))))
 
-(def border
+(def border*
   {:thick BorderStyle/THICK
    :thin BorderStyle/THIN})
 
-(def fill-pattern
+(defn border [value]
+  (get border* value value))
+
+(def fill-pattern*
   {:solid FillPatternType/SOLID_FOREGROUND})
 
+(defn fill-pattern [value]
+  (get fill-pattern* value value))
+
 (defn cell-style [^Workbook wb
                   {:keys [background-color foreground-color
                           border-bottom border-left border-right border-top
-                          wrap]
+                          wrap
+                          build]
                    :as options}]
   (let [^CellStyle cell-style (.createCellStyle wb)
         xssf? (or (instance? XSSFWorkbook wb) (instance? SXSSFWorkbook wb))]
@@ -239,6 +249,8 @@
       (.setDataFormat cell-style (data-format wb (:data-format options))))
     (if wrap
       (.setWrapText cell-style true))
+    (when build
+      (build cell-style))
     cell-style))
 
 (defn write-row! [^Sheet sheet options row-num data]
@@ -248,7 +260,9 @@
         (do
           (if (:height data)
             (.setHeightInPoints row (:height data)))
-          (write-cells! row options (:values data)))
+          (write-cells! row options (:values data))
+          (when-let [f (:build data)]
+            (f row)))
         (write-cells! row options data)))))
 
 (defn write-rows! [^Workbook wb ^Sheet sheet options rows]
diff --git a/test/loiste/core_test.clj b/test/loiste/core_test.clj
index 607ef42..61d44a0 100644
--- a/test/loiste/core_test.clj
+++ b/test/loiste/core_test.clj
@@ -1,8 +1,11 @@
 (ns loiste.core-test
-  (:require [clojure.test :refer [deftest testing is]]
-            [loiste.core :as l]
-            [clojure.java.io :as io])
-  (:import [java.io File]))
+  (:require
+   [clojure.java.io :as io]
+   [clojure.test :refer [deftest is testing]]
+   [loiste.core :as l])
+  (:import
+   [java.io File]
+   [org.apache.poi.ss.usermodel IndexedColors]))
 
 (def test-spec
   [[:A]
@@ -72,24 +75,40 @@
                     :currency {:data-format {:type :custom :format-str "#0\\,00 €"}}
                     :header {:font {:bold true}
                              :border-bottom :thick
-                             :border-right :thin
+                             :border-right org.apache.poi.ss.usermodel.BorderStyle/THIN
                              :fill-pattern :solid
                              :foreground-color (l/color 200 200 200)}
-                    :wrapping-text {:wrap true}}
+                    :wrapping-text {:wrap true}
+                    :interop-style {:build (fn [cell-style]
+                                             (.setWrapText cell-style true))}}
            :columns [{:width (l/column-width 10)}
                      {:width (l/column-width 15) :style :date}
                      {:width (l/column-width 10) :style :currency}]}
           [[{:style :header :value "Stuff"}
             {:style :header :value "Date"}
             {:style :header :value "Money"}]
-           {:height 100
+           {:build (fn [row]
+                     (.setHeightInPoints row 40))
             :values [{:style :wrapping-text
                       :value "This is a long text that should wrap"}
                      #inst "2016-03-09T14:05:00"]}
            ["Bar" #inst "2016-03-09T14:05:00" 15]
            ["Qux" 100000 100]
            ["Integer" (count '(1 2 3)) 10000]
-           ["Keyword" :foo nil]])
+           ["Keyword" :foo nil]
+           {:height 20
+            :values ["Interop"
+                     {:style :interop-style
+                      :build (fn [cell]
+                               (.setCellValue cell (doto (org.apache.poi.xssf.usermodel.XSSFRichTextString.)
+                                                     ;; Shouldn't call font many times, instead initialize different fonts for workbook and then
+                                                     ;; use those.
+                                                     (.append "foo" (l/font wb {:color (.. IndexedColors -RED -index)}))
+                                                     (.append "bar" (l/font wb {:color (.. IndexedColors -GREEN -index)}))
+                                                     (.append "!!!" (l/font wb {:color (.. IndexedColors -BLUE -index)})))))}
+                     {:style :interop-style
+                      :build (fn [cell]
+                               (.setCellFormula cell "C3+C5"))}]}])
 
         (l/to-file! file wb)))
 
@@ -99,7 +118,8 @@
                 {:Stuff "Bar" :Date #inst "2016-03-09T14:05:00" :Money 15.0}
                 {:Stuff "Qux" :Date #inst "2173-10-13T21:00:00.000-00:00" :Money 100.0}
                 {:Stuff "Integer" :Date #inst "1900-01-02T22:20:11.000-00:00" :Money 10000.0}
-                {:Stuff "Keyword" :Date "foo" :Money nil}]
+                {:Stuff "Keyword" :Date "foo" :Money nil}
+                {:Stuff "Interop" :Date "foobar!!!" :Money nil}]
                (l/read-sheet read-sheet)))))
 
     (.delete file)))