diff --git a/lib/carto/parser.js b/lib/carto/parser.js
index 34229a4..74f6033 100644
--- a/lib/carto/parser.js
+++ b/lib/carto/parser.js
@@ -596,6 +596,9 @@ carto.Parser = function Parser(env) {
                     (op = $(this.entities.comparison)) &&
                     (val = $(this.entities.variable) || $(this.entities.dimension)) && $(']')) {
                         return new tree.Zoom(op, val, memo);
+                } else {
+                    // backtrack
+                    restore();
                 }
             },