diff --git a/src/parse.spec.ts b/src/parse.spec.ts
index 9ebe3738..904bc141 100644
--- a/src/parse.spec.ts
+++ b/src/parse.spec.ts
@@ -18,3 +18,26 @@ describe("Collected selectors", () => {
         }
     });
 });
+
+const broken = [
+    "[",
+    "(",
+    "{",
+    "()",
+    "<>",
+    "{}",
+    ",",
+    ",a",
+    "a,",
+    "[id=012345678901234567890123456789",
+    "input[name=foo.baz]",
+    "input[name=foo[baz]]",
+];
+
+describe("Broken selectors", () => {
+    for (const selector of broken) {
+        it(`should not parse — ${selector}`, () => {
+            expect(() => parse(selector)).toThrow(Error);
+        });
+    }
+});
diff --git a/src/parse.ts b/src/parse.ts
index 1f98cf1c..2b1ad3b6 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -211,6 +211,12 @@ function parseSelector(
         return (slashCount & 1) === 1;
     }
 
+    function ensureNotTraversal() {
+        if (tokens.length > 0 && isTraversal(tokens[tokens.length - 1])) {
+            throw new Error("Did not expect successive traversals.");
+        }
+    }
+
     stripWhitespace(0);
 
     while (selector !== "") {
@@ -220,6 +226,7 @@ function parseSelector(
             sawWS = true;
             stripWhitespace(1);
         } else if (firstChar in Traversals) {
+            ensureNotTraversal();
             tokens.push({ type: Traversals[firstChar] });
             sawWS = false;
 
@@ -235,6 +242,7 @@ function parseSelector(
         } else {
             if (sawWS) {
                 if (tokens.length > 0) {
+                    ensureNotTraversal();
                     tokens.push({ type: "descendant" });
                 }
                 sawWS = false;