diff --git a/src/openseadragon.js b/src/openseadragon.js
index 8ecd2f3b..6840e53d 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -2586,8 +2586,13 @@ function OpenSeadragon( options ){
             sep  = part.indexOf( '=' );
 
             if ( sep > 0 ) {
-                URLPARAMS[ part.substring( 0, sep ) ] =
-                    decodeURIComponent( part.substring( sep + 1 ) );
+                var key = part.substring( 0, sep ),
+                    value = part.substring( sep + 1 );
+                try {
+                    URLPARAMS[ key ] = decodeURIComponent( value );
+                } catch (e) {
+                    $.console.error( "Ignoring malformed URL parameter: %s=%s", key, value );
+                }
             }
         }