diff --git a/sites/all/modules/img_assist/img_assist.module b/sites/all/modules/img_assist/img_assist.module
index 3aa560e..7f02aec 100644
--- a/sites/all/modules/img_assist/img_assist.module
+++ b/sites/all/modules/img_assist/img_assist.module
@@ -1261,7 +1261,7 @@ function img_assist_render_image($attributes = array()) {
     // Get size.
     $width  = $attributes['width'];
     $height = $attributes['height'];
-    if ($width && $height) {
+    if ($width || $height) {
       // Check to ensure that the dimensions don't exceed the max set in the
       // img_assist settings.
       $max_size = explode('x', variable_get('img_assist_max_size', '640x640'));
@@ -1286,11 +1286,13 @@ function img_assist_render_image($attributes = array()) {
           $aspect_ratio = round($preview_width / $preview_height, 6);
           
           // Get new width and height for this inline image.
-          // Width is controlling factor.
-          if (round($width / $aspect_ratio) <= $height) {
+          // If height is either left out or larger than width then
+          // width is the controlling factor.
+          if (!$height || round($width / $aspect_ratio) <= $height) {
             $height = round($width / $aspect_ratio);
           }
-          // Height is controlling factor.
+          // Else, width is either left out or larger than height so
+          // height is controlling factor.
           else {
             $width = round($height * $aspect_ratio);
           }