diff --git a/UI/PreferencesUI/UIxPreferences.m b/UI/PreferencesUI/UIxPreferences.m
index 7ff36bd07..c95f15035 100644
--- a/UI/PreferencesUI/UIxPreferences.m
+++ b/UI/PreferencesUI/UIxPreferences.m
@@ -1385,7 +1385,9 @@ static NSArray *reminderValues = nil;
             for (identity in previousIdentities) {
               if ([newIdentitiesAsDict objectForKey: [identity objectForKey:@"email"]]) {
                   [identity setObject: [[newIdentitiesAsDict objectForKey: [identity objectForKey:@"email"]] objectForKey:@"fullName"] forKey: @"fullName"];
-                  [identity setObject: [[newIdentitiesAsDict objectForKey: [identity objectForKey:@"email"]] objectForKey:@"signature"] forKey: @"signature"];
+                  if ([identity objectForKey:@"signature"]) {
+                    [identity setObject: [[newIdentitiesAsDict objectForKey: [identity objectForKey:@"email"]] objectForKey:@"signature"] forKey: @"signature"];
+                  }
                   if ([[newIdentitiesAsDict objectForKey: [identity objectForKey:@"email"]] objectForKey:@"isDefault"]) {
                     [identity setObject: [NSNumber numberWithBool: YES] forKey: @"isDefault"];
                   } else {