diff --git a/ext/bg/js/options-form.js b/ext/bg/js/options-form.js
index 239b09d5..d515b789 100644
--- a/ext/bg/js/options-form.js
+++ b/ext/bg/js/options-form.js
@@ -40,7 +40,7 @@ function formToOptions(section, callback) {
 
         switch (section) {
             case 'general':
-                optsNew.scanLength        = $('#scan-length').val();
+                optsNew.scanLength        = parseInt($('#scan-length').val());
                 optsNew.activateOnStartup = $('#activate-on-startup').prop('checked');
                 optsNew.loadEnamDict      = $('#load-enamdict').prop('checked');
                 optsNew.selectMatchedText = $('#select-matched-text').prop('checked');
diff --git a/ext/bg/js/options.js b/ext/bg/js/options.js
index f131ab9b..0a5197f9 100644
--- a/ext/bg/js/options.js
+++ b/ext/bg/js/options.js
@@ -38,6 +38,8 @@ function sanitizeOptions(options) {
         }
     }
 
+    options.scanLength = parseInt(options.scanLength);
+
     return options;
 }
 
diff --git a/ext/fg/js/range.js b/ext/fg/js/range.js
index 0cf79ddf..f6af7122 100644
--- a/ext/fg/js/range.js
+++ b/ext/fg/js/range.js
@@ -27,16 +27,29 @@ class Range {
     }
 
     setLength(length) {
-        const node   = this.rng.startContainer;
-        const offset = this.rng.startOffset;
+        const end = this.findEnd(this.rng.startContainer, this.rng.startOffset, length);
+        this.rng.setEnd(end.node, end.offset);
+    }
 
-        length = Math.min(node.length - offset, length);
-        if (length === 0) {
-            return null;
+    findEnd(node, offset, length) {
+        if (node.nodeType === 3) {
+            const remainder = node.data.length - offset;
+            if (remainder >= length) {
+                return {node, offset: offset + length};
+            }
+
+            length -= remainder;
         }
 
-        this.rng.setEnd(node, offset + length);
-        return length;
+        if (node.childNodes.length > 0) {
+            return this.findEnd(node.childNodes[0], 0, length);
+        }
+
+        if (node.nextSibling !== null) {
+            return this.findEnd(node.nextSibling, 0, length);
+        }
+
+        return {node, offset: node.data.length};
     }
 
     containsPoint(point) {