diff --git a/browser/devtools/scratchpad/scratchpad.js b/browser/devtools/scratchpad/scratchpad.js
index a1f134ae648..47d9bcc5a96 100644
--- a/browser/devtools/scratchpad/scratchpad.js
+++ b/browser/devtools/scratchpad/scratchpad.js
@@ -419,8 +419,7 @@ var Scratchpad = {
         this.writeAsErrorComment(aError.exception).then(resolve, reject);
       }
       else if (VariablesView.isPrimitive({ value: aResult })) {
-        this.writeAsComment(aResult.type || aResult);
-        resolve();
+        this._writePrimitiveAsComment(aResult).then(resolve, reject);
       }
       else {
         this.deselect();
@@ -488,13 +487,13 @@ var Scratchpad = {
         this.writeAsErrorComment(aError.exception).then(resolve, reject);
       }
       else if (VariablesView.isPrimitive({ value: aResult })) {
-        this.writeAsComment(aResult.type || aResult);
-        resolve();
+        this._writePrimitiveAsComment(aResult).then(resolve, reject);
       }
       else {
         let gripClient = new GripClient(this.debuggerClient, aResult);
         gripClient.getDisplayString(aResponse => {
           if (aResponse.error) {
+            reportError("display", aResponse);
             reject(aResponse);
           }
           else {
@@ -513,6 +512,41 @@ var Scratchpad = {
     return deferred.promise;
   },
 
+  /**
+   * Writes out a primitive value as a comment. This handles values which are
+   * to be printed directly (number, string) as well as grips to values
+   * (null, undefined, longString).
+   *
+   * @param any aValue
+   *        The value to print.
+   * @return Promise
+   *         The promise that resolves after the value has been printed.
+   */
+  _writePrimitiveAsComment: function SP__writePrimitiveAsComment(aValue)
+  {
+    let deferred = promise.defer();
+
+    if (aValue.type == "longString") {
+      let client = this.webConsoleClient;
+      client.longString(aValue).substring(0, aValue.length, aResponse => {
+        if (aResponse.error) {
+          reportError("display", aResponse);
+          deferred.reject(aResponse);
+        }
+        else {
+          deferred.resolve(aResponse.substring);
+        }
+      });
+    }
+    else {
+      deferred.resolve(aValue.type || aValue);
+    }
+
+    return deferred.promise.then(aComment => {
+      this.writeAsComment(aComment);
+    });
+  },
+
   /**
    * Write out a value at the next line from the current insertion point.
    * The comment block will always be preceded by a newline character.
diff --git a/browser/devtools/scratchpad/test/Makefile.in b/browser/devtools/scratchpad/test/Makefile.in
index 76945eb013f..570b79737dc 100644
--- a/browser/devtools/scratchpad/test/Makefile.in
+++ b/browser/devtools/scratchpad/test/Makefile.in
@@ -37,6 +37,7 @@ MOCHITEST_BROWSER_FILES = \
 		browser_scratchpad_bug_661762_wrong_window_focus.js \
 		browser_scratchpad_bug_644413_modeline.js \
 		browser_scratchpad_bug807924_cannot_convert_to_string.js \
+		browser_scratchpad_long_string.js \
 		head.js \
 
 # Disable test due to bug 807234 becoming basically permanent
diff --git a/browser/devtools/scratchpad/test/browser_scratchpad_long_string.js b/browser/devtools/scratchpad/test/browser_scratchpad_long_string.js
new file mode 100644
index 00000000000..d85a7df1cb5
--- /dev/null
+++ b/browser/devtools/scratchpad/test/browser_scratchpad_long_string.js
@@ -0,0 +1,30 @@
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test()
+{
+  waitForExplicitFinish();
+
+  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedBrowser.addEventListener("load", function onLoad() {
+    gBrowser.selectedBrowser.removeEventListener("load", onLoad, true);
+    openScratchpad(runTests);
+  }, true);
+
+  content.location = "data:text/html;charset=utf8,<p>test long string in Scratchpad</p>";
+}
+
+function runTests()
+{
+  let sp = gScratchpadWindow.Scratchpad;
+
+  sp.setText("'0'.repeat(10000)");
+
+  sp.display().then(() => {
+    is(sp.getText(), "'0'.repeat(10000)\n" +
+                     "/*\n" + "0".repeat(10000) + "\n*/",
+       "display()ing a long string works");
+    finish();
+  });
+}