diff --git a/browser/locales/en-US/chrome/browser/downloads/downloads.dtd b/browser/locales/en-US/chrome/browser/downloads/downloads.dtd
index feabcc8696b1..4a96d3a0fe2a 100644
--- a/browser/locales/en-US/chrome/browser/downloads/downloads.dtd
+++ b/browser/locales/en-US/chrome/browser/downloads/downloads.dtd
@@ -66,6 +66,33 @@
 <!ENTITY cmd.clearList.accesskey          "a">
 <!ENTITY cmd.clearDownloads.label         "Clear Downloads">
 <!ENTITY cmd.clearDownloads.accesskey     "D">
+<!-- LOCALIZATION NOTE (cmd.unblock.label):
+     This command may be shown in the context menu, as a menu button item, or as
+     a text link when malware or potentially unwanted downloads are blocked.
+     Note: This string doesn't exist in the UI yet.  See bug 1053890.
+     -->
+<!ENTITY cmd.unblock.label                "Unblock">
+<!ENTITY cmd.unblock.accesskey            "U">
+<!-- LOCALIZATION NOTE (cmd.removeFile.label):
+     This command may be shown in the context menu or as a menu button label
+     when malware or potentially unwanted downloads are blocked.
+     Note: This string doesn't exist in the UI yet.  See bug 1053890.
+     -->
+<!ENTITY cmd.removeFile.label             "Remove File">
+<!ENTITY cmd.removeFile.accesskey         "m">
+
+<!-- LOCALIZATION NOTE (blocked.label):
+     Shown as a tag before the file name for some types of blocked downloads.
+     Note: This string doesn't exist in the UI yet.  See bug 1053890.
+     -->
+<!ENTITY blocked.label                    "BLOCKED">
+
+<!-- LOCALIZATION NOTE (learnMore.label):
+     Shown as a text link for some types of blocked downloads, for example
+     malware, when there is an associated explanation page on the Mozilla site.
+     Note: This string doesn't exist in the UI yet.  See bug 1053890.
+     -->
+<!ENTITY learnMore.label                  "Learn More">
 
 <!-- LOCALIZATION NOTE (downloadsHistory.label, downloadsHistory.accesskey):
      This string is shown at the bottom of the Downloads Panel when all the
diff --git a/browser/locales/en-US/chrome/browser/downloads/downloads.properties b/browser/locales/en-US/chrome/browser/downloads/downloads.properties
index 761abf61af57..f49279ade8cb 100644
--- a/browser/locales/en-US/chrome/browser/downloads/downloads.properties
+++ b/browser/locales/en-US/chrome/browser/downloads/downloads.properties
@@ -38,13 +38,40 @@ stateBlockedPolicy=Blocked by your security zone policy
 # Indicates that the download was blocked after scanning.
 stateDirty=Blocked: May contain a virus or spyware
 
+# LOCALIZATION NOTE (blockedMalware, blockedPotentiallyUnwanted,
+#                    blockedUncommon):
+# These strings are shown in the panel for some types of blocked downloads, and
+# are immediately followed by the "Learn More" link, thus they must end with a
+# period.  You may need to adjust "downloadDetails.width" in "downloads.dtd" if
+# this turns out to be longer than the other existing status strings.
+# Note: These strings don't exist in the UI yet.  See bug 1053890.
+blockedMalware=This file contains a virus or malware.
+blockedPotentiallyUnwanted=This file may harm your computer.
+blockedUncommon=This file may not be safe to open.
+
+# LOCALIZATION NOTE (unblockHeader, unblockTypeMalware,
+#                    unblockTypePotentiallyUnwanted, unblockTypeUncommon,
+#                    unblockTip, unblockButtonContinue, unblockButtonCancel):
+# These strings are displayed in the dialog shown when the user asks a blocked
+# download to be unblocked.  The severity of the threat is expressed in
+# descending order by the unblockType strings, it is higher for files detected
+# as malware and lower for uncommon downloads.
+# Note: These strings don't exist in the UI yet.  See bug 1053890.
+unblockHeader=Are you sure you want to unblock this file?
+unblockTypeMalware=This file contains a virus or other malware that will harm your computer.
+unblockTypePotentiallyUnwanted=This file, disguised as a helpful download, will make unexpected changes to your programs and settings.
+unblockTypeUncommon=This file has been downloaded from an unfamiliar and potentially dangerous website and may not be safe to open.
+unblockTip=You can search for an alternate download source or try to download the file again later.
+unblockButtonContinue=Unblock anyway
+unblockButtonCancel=Keep me safe
+
 # LOCALIZATION NOTE (sizeWithUnits):
 # %1$S is replaced with the size number, and %2$S with the measurement unit.
 sizeWithUnits=%1$S %2$S
 sizeUnknown=Unknown size
 
 # LOCALIZATION NOTE (shortTimeLeftSeconds, shortTimeLeftMinutes,
-# shortTimeLeftHours, shortTimeLeftDays):
+#                    shortTimeLeftHours, shortTimeLeftDays):
 # These values are displayed in the downloads indicator in the main browser
 # window, where space is available for three characters maximum.  %1$S is
 # replaced with the time left for the given measurement unit.  Even for days,