diff --git a/common/content/buffer.js b/common/content/buffer.js
index e7879b8d..3e645678 100644
--- a/common/content/buffer.js
+++ b/common/content/buffer.js
@@ -1639,11 +1639,13 @@ const Buffer = Module("buffer", {
     options: function () {
         options.add(["nextpattern"],
             "Patterns to use when guessing the 'next' page in a document sequence",
-            "stringlist", UTF8("\\bnext\\b,^>$,^(>>|»)$,^(>|»),(>|»)$,\\bmore\\b"));
+            "stringlist", UTF8("\\bnext\\b,^>$,^(>>|»)$,^(>|»),(>|»)$,\\bmore\\b"),
+            { validator: Option.validateXPath });
 
         options.add(["previouspattern"],
             "Patterns to use when guessing the 'previous' page in a document sequence",
-            "stringlist", UTF8("\\bprev|previous\\b,^<$,^(<<|«)$,^(<|«),(<|«)$"));
+            "stringlist", UTF8("\\bprev|previous\\b,^<$,^(<<|«)$,^(<|«),(<|«)$"),
+            { validator: Option.validateXPath });
 
         options.add(["pageinfo", "pa"],
             "Desired info in the :pageinfo output",
diff --git a/common/content/commandline.js b/common/content/commandline.js
index d49568e5..54ff49f2 100644
--- a/common/content/commandline.js
+++ b/common/content/commandline.js
@@ -770,7 +770,7 @@ const CommandLine = Module("commandline", {
                 // FIXME: <Esc> should trigger "cancel" event
                 if (events.isAcceptKey(key)) {
                     let mode = this._currentExtendedMode; // save it here, as modes.pop() resets it
-                    this._keepCommand = !userContext.hidden_option_command_afterimage;
+                    this._keepCommand = userContext.hidden_option_command_afterimage;
                     this._currentExtendedMode = null; // Don't let modes.pop trigger "cancel"
                     modes.pop();
                     commandline.triggerCallback("submit", mode, command);
diff --git a/common/content/hints.js b/common/content/hints.js
index f9780551..6fb546c6 100644
--- a/common/content/hints.js
+++ b/common/content/hints.js
@@ -1053,25 +1053,15 @@ const Hints = Module("hints", {
             util.makeXPath(["input[not(@type='hidden')]", "a", "area", "iframe", "textarea", "button", "select",
                             "*[@onclick or @onmouseover or @onmousedown or @onmouseup or @oncommand or @role='link']"]);
 
-        function checkXPath(val) {
-            try {
-                util.evaluateXPath(val, document.implementation.createDocument("", "", null));
-                return true;
-            }
-            catch (e) {
-                return false;
-            }
-        }
-
         options.add(["extendedhinttags", "eht"],
             "XPath string of hintable elements activated by ';'",
             "regexmap", "[iI]:" + Option.quote(util.makeXPath(["img"])),
-            { validator: checkXPath });
+            { validator: Option.validateXPath });
 
         options.add(["hinttags", "ht"],
             "XPath string of hintable elements activated by 'f' and 'F'",
             "string", DEFAULT_HINTTAGS,
-            { validator: checkXPath });
+            { validator: Option.validateXPath });
 
         options.add(["hintkeys", "hk"],
             "The keys used to label and select hints",
diff --git a/common/content/options.js b/common/content/options.js
index 619a9cb0..63613df5 100644
--- a/common/content/options.js
+++ b/common/content/options.js
@@ -48,6 +48,9 @@ const Option = Class("Option", {
         if (this.type in Option.joinValues)
             this.joinValues = Option.joinValues[this.type];
 
+        if (this.type in Option.testValues)
+            this.testValues = Option.testValues[this.type];
+
         this._op = Option.ops[this.type];
 
         if (arguments.length > 3) {
@@ -325,6 +328,8 @@ const Option = Class("Option", {
      */
     setter: null,
 
+    testValues: function (values, validator) validator(values),
+
     /**
      * @property {function} The function called to validate the option's value
      *     when set.
@@ -383,7 +388,7 @@ const Option = Class("Option", {
         return re;
     },
     unparseRegex: function (re) re.bang + Option.quote(re.source.replace(/\\(.)/g, function (m, n1) n1 == "/" ? n1 : m), /^!|:/) +
-        (typeof re.result == "string" ? ":" + Option.quote(re.result) : ""),
+        (typeof re.result === "string" ? ":" + Option.quote(re.result) : ""),
 
     getKey: {
         stringlist: function (k) this.values.indexOf(k) >= 0,
@@ -427,6 +432,12 @@ const Option = Class("Option", {
             })
     },
 
+    testValues: {
+        regexmap:   function (vals, validator) vals.every(function (re) validator(re.result)),
+        stringlist: function (vals, validator) vals.every(validator, this),
+        stringmap:  function (vals, validator) array(values(vals)).every(validator, this)
+    },
+
     dequote: function (value) {
         let arg;
         [, arg, Option._quote] = Commands.parseArg(String(value), "");
@@ -556,6 +567,12 @@ const Option = Class("Option", {
         if (this.type == "regexmap")
             return Array.concat(values).every(function (re) res.some(function (item) item[0] == re.result));
         return Array.concat(values).every(function (value) res.some(function (item) item[0] == value));
+    },
+
+    validateXPath: function (values) {
+        let evaluator = XPathEvaluator();
+        return this.testValues(values,
+            function (value) evaluator.createExpression(value, util.evaluateXPath.resolver));
     }
 });
 
diff --git a/common/modules/util.jsm b/common/modules/util.jsm
index e7f3f1cf..c73d30e6 100644
--- a/common/modules/util.jsm
+++ b/common/modules/util.jsm
@@ -275,34 +275,36 @@ const Util = Module("Util", {
      * @param {boolean} asIterator Whether to return the results as an
      *     XPath iterator.
      */
-    evaluateXPath: function (expression, doc, elem, asIterator) {
-        if (!doc)
-            doc = util.activeWindow.content.document;
-        if (!elem)
-            elem = doc;
-        if (isArray(expression))
-            expression = util.makeXPath(expression);
+    evaluateXPath: (function () {
+        function evaluateXPath(expression, doc, elem, asIterator) {
+            if (!doc)
+                doc = util.activeWindow.content.document;
+            if (!elem)
+                elem = doc;
+            if (isArray(expression))
+                expression = util.makeXPath(expression);
 
-        let result = doc.evaluate(expression, elem,
-            function lookupNamespaceURI(prefix) {
-                return {
-                    xul: XUL.uri,
-                    xhtml: XHTML.uri,
-                    xhtml2: "http://www.w3.org/2002/06/xhtml2",
-                    dactyl: NS.uri
-                }[prefix] || null;
-            },
-            asIterator ? Ci.nsIDOMXPathResult.ORDERED_NODE_ITERATOR_TYPE : Ci.nsIDOMXPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
-            null
-        );
+            let result = doc.evaluate(expression, elem,
+                evaluateXPath.resolver,
+                asIterator ? Ci.nsIDOMXPathResult.ORDERED_NODE_ITERATOR_TYPE : Ci.nsIDOMXPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
+                null
+            );
 
-        return Object.create(result, {
-            __iterator__: {
-                value: asIterator ? function () { let elem; while ((elem = this.iterateNext())) yield elem; }
-                                  : function () { for (let i = 0; i < this.snapshotLength; i++) yield this.snapshotItem(i); }
-            }
-        });
-    },
+            return Object.create(result, {
+                __iterator__: {
+                    value: asIterator ? function () { let elem; while ((elem = this.iterateNext())) yield elem; }
+                                      : function () { for (let i = 0; i < this.snapshotLength; i++) yield this.snapshotItem(i); }
+                }
+            });
+        }
+        evaluateXPath.resolver = function lookupNamespaceURI(prefix) ({
+                xul: XUL.uri,
+                xhtml: XHTML.uri,
+                xhtml2: "http://www.w3.org/2002/06/xhtml2",
+                dactyl: NS.uri
+            }[prefix] || null);
+        return evaluateXPath;
+    })(),
 
     extend: function extend(dest) {
         Array.slice(arguments, 1).filter(util.identity).forEach(function (src) {