diff --git a/src/math/Vector2.js b/src/math/Vector2.js
index 75cf640cb6c234d11bfb25483d886fe8bcea527a..9bb3b8ca9682cb7a0c16416dcf12885238acfc13 100644
--- a/src/math/Vector2.js
+++ b/src/math/Vector2.js
@@ -118,7 +118,7 @@ THREE.Vector2.prototype = {
 
 	divideScalar: function ( s ) {
 
-		if ( s ) {
+		if ( s !== 0 ) {
 
 			this.x /= s;
 			this.y /= s;
@@ -244,7 +244,7 @@ THREE.Vector2.prototype = {
 
 		var oldLength = this.length();
 		
-		if( oldLength ) {
+		if ( oldLength !== 0 && l !== oldLength  ) {
 
 			this.multiplyScalar( l / oldLength );
 		}
diff --git a/src/math/Vector3.js b/src/math/Vector3.js
index dd50e236952db98742101b08d7457ff904f130cf..c937d5ca26a1f795ba0f27b9c787d1053f8781f1 100644
--- a/src/math/Vector3.js
+++ b/src/math/Vector3.js
@@ -168,7 +168,7 @@ THREE.Vector3.prototype = {
 
 	divideScalar: function ( s ) {
 
-		if ( s ) {
+		if ( s !== 0 ) {
 
 			this.x /= s;
 			this.y /= s;
@@ -312,7 +312,7 @@ THREE.Vector3.prototype = {
 
 		var oldLength = this.length();
 		
-		if( oldLength ) {
+		if ( oldLength !== 0 && l !== oldLength  ) {
 
 			this.multiplyScalar( l / oldLength );
 		}
diff --git a/src/math/Vector4.js b/src/math/Vector4.js
index 1b1d15b16663a41a52e58485f946f2bde01558ea..d2d1c55074a65c10e3994a947811eac4180af556 100644
--- a/src/math/Vector4.js
+++ b/src/math/Vector4.js
@@ -153,7 +153,7 @@ THREE.Vector4.prototype = {
 
 	divideScalar: function ( s ) {
 
-		if ( s ) {
+		if ( s !== 0 ) {
 
 			this.x /= s;
 			this.y /= s;
@@ -321,7 +321,7 @@ THREE.Vector4.prototype = {
 
 		var oldLength = this.length();
 		
-		if( oldLength ) {
+		if ( oldLength !== 0 && l !== oldLength  ) {
 
 			this.multiplyScalar( l / oldLength );
 		}