1diff --git a/src/Cell.ts b/src/Cell.ts
 2index 01b7af3..fe5f092 100644
 3--- a/src/Cell.ts
 4+++ b/src/Cell.ts
 5@@ -19,7 +19,7 @@ class Cell {
 6     var key = parseKey(id);
 7 
 8     this.formula = null;
 9-    this.value = "";
10+    this.value = null;
11     this.dependencies = [];
12     this.error = null;
13     this.id = id;
14@@ -97,6 +97,19 @@ class Cell {
15     this.value = value;
16   }
17 
18+  /**
19+   * Sets the value or formula for this cell. If the input begins with =, then it is considered to be a formula. If it
20+   * is not, then it is a value, and set as the raw value for this cell.
21+   * @param rawFormula
22+   */
23+  setRawFormula(rawFormula: string) {
24+    if (rawFormula.charAt(0) === "=") {
25+      this.formula = rawFormula.substr(1);
26+    } else {
27+      this.value = rawFormula;
28+    }
29+  }
30+
31   /**
32    * Get the value of this cell. Since value could be null do to an error in the formula, this could return null.
33    * @returns {string}
34diff --git a/src/Sheet.ts b/src/Sheet.ts
35index d8288aa..40927f7 100644
36--- a/src/Sheet.ts
37+++ b/src/Sheet.ts
38@@ -88,7 +88,12 @@ var Sheet = (function () {
39         this.data[cellId] = cell;
40       } else {
41         this.getCell(cellId).updateDependencies(cell.getDependencies());
42-        this.getCell(cellId).setValue(cell.getValue());
43+        var cellValue = cell.getValue();
44+        if (cellValue === null) {
45+          this.getCell(cellId).clearValue();
46+        } else {
47+          this.getCell(cellId).setValue(cellValue);
48+        }
49         this.getCell(cellId).setError(cell.getError());
50       }
51 
52@@ -149,11 +154,7 @@ var Sheet = (function () {
53      */
54     setCell(id: string, rawFormula: string) {
55       var cell = new Cell(id);
56-      if (rawFormula.charAt(0) === "=") {
57-        cell.setFormula(rawFormula.substr(1));
58-      } else {
59-        cell.setValue(rawFormula);
60-      }
61+      cell.setRawFormula(rawFormula);
62       registerCellInMatrix(cell);
63       recalculateCellDependencies(cell);
64     }