diff --git a/index.js b/index.js
index 1e05689..7caf82a 100644
--- a/index.js
+++ b/index.js
@@ -41,6 +41,7 @@ function parse(_) {
         white();
         var depth = 0, rings = [], stack = [rings],
             pointer = rings, elem;
+
         while (elem =
             $(/^(\()/) ||
             $(/^(\))/) ||
@@ -49,21 +50,25 @@ function parse(_) {
             if (elem == '(') {
                 stack.push(pointer);
                 pointer = [];
-                stack[stack.length-1].push(pointer);
+                stack[stack.length - 1].push(pointer);
                 depth++;
             } else if (elem == ')') {
                 pointer = stack.pop();
+                // the stack was empty, input was malformed
+                if (!pointer) return;
                 depth--;
-                if (depth == 0) break;
+                if (depth === 0) break;
             } else if (elem === ',') {
                 pointer = [];
-                stack[stack.length-1].push(pointer);
-            } else {
+                stack[stack.length - 1].push(pointer);
+            } else if (!isNaN(parseFloat(elem))) {
                 pointer.push(parseFloat(elem));
+            } else {
+                return null;
             }
             white();
         }
-        stack.length = 0;
+
         if (depth !== 0) return null;
         return rings;
     }
@@ -91,6 +96,7 @@ function parse(_) {
         white();
         if (!$(/^(\()/)) return null;
         var c = coords();
+        if (!c) return null;
         white();
         if (!$(/^(\))/)) return null;
         return {
@@ -103,6 +109,7 @@ function parse(_) {
         if (!$(/^(multipoint)/i)) return null;
         white();
         var c = multicoords();
+        if (!c) return null;
         white();
         return {
             type: 'MultiPoint',
@@ -114,6 +121,7 @@ function parse(_) {
         if (!$(/^(multilinestring)/i)) return null;
         white();
         var c = multicoords();
+        if (!c) return null;
         white();
         return {
             type: 'MultiLineString',
@@ -126,6 +134,7 @@ function parse(_) {
         white();
         if (!$(/^(\()/)) return null;
         var c = coords();
+        if (!c) return null;
         if (!$(/^(\))/)) return null;
         return {
             type: 'LineString',
diff --git a/package.json b/package.json
index 731499b..aaec865 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,8 @@
   "devDependencies": {
     "tape": "~2.4.2",
     "brfs": "~0.2.1",
-    "testling": "~1.6.0"
+    "testling": "~1.6.0",
+    "fuzzer": "~0.1.0"
   },
   "dependencies": {
     "concat-stream": "~1.0.1",
@@ -46,4 +47,3 @@
     "sharkdown": "0.0.1"
   }
 }
-
diff --git a/test/wellknown.test.js b/test/wellknown.test.js
index 4b51037..45c639b 100644
--- a/test/wellknown.test.js
+++ b/test/wellknown.test.js
@@ -1,6 +1,7 @@
 var parse = require('../'),
-fs = require('fs'),
-test = require('tape').test;
+    fs = require('fs'),
+    fuzzer = require('fuzzer'),
+    test = require('tape').test;
 
 test('wellknown', function(t) {
     t.deepEqual(parse('POINT (1 1)'), {
@@ -192,3 +193,23 @@ test('wellknown', function(t) {
 
     t.end();
 });
+
+test('fuzz', function(t) {
+    fuzzer.seed(0);
+    var inputs = [
+        'MULTIPOLYGON (((30 20, 10 40, 45 40, 30 20)), ((15 5, 40 10, 10 20, 5 10, 15 5)))',
+        'POINT(1.1 1.1)',
+        'LINESTRING (30 10, 10 30, 40 40)',
+        'GeometryCollection(POINT(4 6),\nLINESTRING(4 6,7 10))'];
+    inputs.forEach(function(str) {
+        for (var i = 0; i < 10000; i++) {
+            try {
+                var input = fuzzer.mutate.string(str);
+                parse(input);
+            } catch(e) {
+                t.fail('could not parse ' + input + ', exception ' + e + '\n' + e.stack);
+            }
+        }
+    });
+    t.end();
+});