diff --git a/src/WPStrava/StaticMap.php b/src/WPStrava/StaticMap.php
index 3c12850..2b272ac 100644
--- a/src/WPStrava/StaticMap.php
+++ b/src/WPStrava/StaticMap.php
@@ -24,6 +24,11 @@ public static function get_image_tag( $activity, $height = 320, $width = 480, $m
 			return '';
 		}
 
+		if ( ! $height || ! $width ) {
+			$height = 320;
+			$width  = 480;
+		}
+
 		$url       = "https://maps.googleapis.com/maps/api/staticmap?maptype=terrain&size={$width}x{$height}&scale=2&sensor=false&key={$key}&path=color:0xFF0000BF|weight:2|enc:";
 		$url_len   = strlen( $url );
 		$max_chars = 1865;