diff --git a/UpdateEngine.conf b/UpdateEngine.conf
index ac40e9d..bdfd3c8 100644
--- a/UpdateEngine.conf
+++ b/UpdateEngine.conf
@@ -48,6 +48,9 @@
     <allow send_destination="org.chromium.UpdateEngine"
            send_interface="org.chromium.UpdateEngineInterface"
            send_member="GetDurationSinceUpdate"/>
+    <allow send_destination="org.chromium.UpdateEngine"
+           send_interface="org.chromium.UpdateEngineInterface"
+           send_member="GetOldVersion"/>
     <allow send_interface="org.chromium.UpdateEngineLibcrosProxyResolvedInterface" />
   </policy>
   <policy user="power">
diff --git a/dbus_service.cc b/dbus_service.cc
index a9455fe..7235be1 100644
--- a/dbus_service.cc
+++ b/dbus_service.cc
@@ -481,3 +481,12 @@
                 new_size);
   return TRUE;
 }
+
+gboolean update_engine_service_get_prev_version(
+    UpdateEngineService* self,
+    gchar** prev_version,
+    GError **error) {
+  std::string ver = self->system_state_->update_attempter()->GetPrevVersion();
+  *prev_version = g_strdup(ver.c_str());
+  return TRUE;
+}
diff --git a/dbus_service.h b/dbus_service.h
index cb8c0e2..3449f1f 100644
--- a/dbus_service.h
+++ b/dbus_service.h
@@ -151,6 +151,14 @@
     const gchar* new_version,
     gint64 new_size);
 
+// Returns the version string of OS that was used before the last reboot
+// into an updated version. This is avalable only when rebooting into an
+// update from previous version, otherwise an empty string is returned.
+gboolean update_engine_service_get_prev_version(
+    UpdateEngineService* self,
+    gchar** prev_version,
+    GError **error);
+
 G_END_DECLS
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_DBUS_SERVICE_H_
diff --git a/update_attempter.cc b/update_attempter.cc
index 9cb7a25..5ab8e1a 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -1456,6 +1456,20 @@
 
 
 void UpdateAttempter::UpdateEngineStarted() {
+  // If we just booted into a new update, keep the previous OS version
+  // in case we rebooted because of a crash of the old version, so we
+  // can do a proper crash report with correcy information.
+  // This must be done before calling
+  // system_state_->payload_state()->UpdateEngineStarted() since it will
+  // delete SystemUpdated marker file.
+  if (system_state_->system_rebooted() &&
+      prefs_->Exists(kPrefsSystemUpdatedMarker)) {
+    if (!prefs_->GetString(kPrefsPreviousVersion, &prev_version_)) {
+      // If we fail to get the version string, make sure it stays empty.
+      prev_version_.clear();
+    }
+  }
+
   system_state_->payload_state()->UpdateEngineStarted();
   StartP2PAtStartup();
 }
diff --git a/update_attempter.h b/update_attempter.h
index 216d3c1..425d8ed 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -187,6 +187,11 @@
   // successful update. Returns false if the device has not updated.
   bool GetBootTimeAtUpdate(base::Time *out_boot_time);
 
+  // Returns a version OS version that was being used before the last reboot,
+  // and if that reboot happended to be into an update (current version).
+  // This will return an empty string otherwise.
+  std::string const& GetPrevVersion() const { return prev_version_; }
+
  private:
   // Update server URL for automated lab test.
   static const char* const kTestUpdateUrl;
@@ -395,6 +400,7 @@
   UpdateStatus status_;
   double download_progress_;
   int64_t last_checked_time_;
+  std::string prev_version_;
   std::string new_version_;
   int64_t new_payload_size_;
 
diff --git a/update_engine.xml b/update_engine.xml
index 964ea62..3891374 100644
--- a/update_engine.xml
+++ b/update_engine.xml
@@ -78,5 +78,8 @@
       <arg type="s" name="new_version" />
       <arg type="x" name="new_size" />
     </signal>
+    <method name="GetPrevVersion">
+      <arg type="s" name="prev_version" direction="out" />
+    </method>
   </interface>
 </node>
diff --git a/update_engine_client.cc b/update_engine_client.cc
index 6bd3d9f..d27f027 100644
--- a/update_engine_client.cc
+++ b/update_engine_client.cc
@@ -57,6 +57,8 @@
               "cellular networks.");
 DEFINE_bool(watch_for_updates, false,
             "Listen for status updates and print them to the screen.");
+DEFINE_bool(prev_version, false,
+            "Show the previous OS version used before the update reboot.");
 
 namespace {
 
@@ -373,6 +375,26 @@
   g_main_loop_unref(loop);
 }
 
+void ShowPrevVersion() {
+  DBusGProxy* proxy;
+  GError* error = nullptr;
+
+  CHECK(GetProxy(&proxy));
+
+  char* prev_version = nullptr;
+
+  gboolean rc = update_engine_client_get_prev_version(proxy,
+                                                      &prev_version,
+                                                      &error);
+  if (!rc) {
+    LOG(ERROR) << "Error getting previous version: "
+               << GetAndFreeGError(&error);
+  } else {
+    LOG(INFO) << "Previous version = " << prev_version;
+    g_free(prev_version);
+  }
+}
+
 }  // namespace {}
 
 int main(int argc, char** argv) {
@@ -521,6 +543,10 @@
     return 0;
   }
 
+  if (FLAGS_prev_version) {
+    ShowPrevVersion();
+  }
+
   LOG(INFO) << "Done.";
   return 0;
 }