diff --git a/spec/parser/javascript/repeat_spec_spec.js b/spec/parser/javascript/repeat_spec_spec.js
index 61eadb2..4d79cc7 100644
--- a/spec/parser/javascript/repeat_spec_spec.js
+++ b/spec/parser/javascript/repeat_spec_spec.js
@@ -31,4 +31,11 @@ describe('parser/javascript/repeat_spec.js', function() {
     expect(parser.__consume__repeat_spec()).toEqual(null);
   });
 
+  it('throws an exception when the numbers are out of order', function() {
+    var parser = new javascript.Parser('{42,24}');
+    expect(() => {
+      parser.__consume__repeat_spec();
+    }).toThrow('Numbers out of order: {42,24}');
+  });
+
 });
diff --git a/src/js/parser/javascript/repeat_spec.js b/src/js/parser/javascript/repeat_spec.js
index cf1eb7e..d6ee5d0 100644
--- a/src/js/parser/javascript/repeat_spec.js
+++ b/src/js/parser/javascript/repeat_spec.js
@@ -15,5 +15,9 @@ export default {
     } else {
       this.maximum = -1;
     }
+
+    if (this.minimum > this.maximum && this.maximum !== -1) {
+      throw `Numbers out of order: ${this.textValue}`;
+    }
   }
 };