diff --git a/modules/comment.module b/modules/comment.module
index 9baf10ce98bf560e80c486335ddcfb2f5624747a..bc663a3ec0b159fdb7576feda7a936344c1fbc7e 100644
--- a/modules/comment.module
+++ b/modules/comment.module
@@ -44,9 +44,15 @@ function comment_conf_options() {
 function comment_user($type, $edit, &$user) {
   switch ($type) {
     case "view_public":
-      return form_item(t("Signature"), check_output($user->signature, 1));
+      if ($user->signature) {
+        return form_item(t("Signature"), check_output($user->signature, 1));
+      }
+      break;
     case "view_private":
-      return form_item(t("Signature"), check_output($user->signature, 1));
+      if ($user->signature) {
+        return form_item(t("Signature"), check_output($user->signature, 1));
+      }
+      break;
     case "edit_form":
       // when user tries to edit his own data
       return form_textarea(t("Signature"), "signature", $edit["signature"], 70, 3, t("Your signature will be publicly displayed at the end of your comments.") ."<br />". t("Allowed HTML tags") .": ". htmlspecialchars(variable_get("allowed_html", "<a> <b> <dd> <dl> <dt> <i> <li> <ol> <u> <ul>")));
diff --git a/modules/comment/comment.module b/modules/comment/comment.module
index 9baf10ce98bf560e80c486335ddcfb2f5624747a..bc663a3ec0b159fdb7576feda7a936344c1fbc7e 100644
--- a/modules/comment/comment.module
+++ b/modules/comment/comment.module
@@ -44,9 +44,15 @@ function comment_conf_options() {
 function comment_user($type, $edit, &$user) {
   switch ($type) {
     case "view_public":
-      return form_item(t("Signature"), check_output($user->signature, 1));
+      if ($user->signature) {
+        return form_item(t("Signature"), check_output($user->signature, 1));
+      }
+      break;
     case "view_private":
-      return form_item(t("Signature"), check_output($user->signature, 1));
+      if ($user->signature) {
+        return form_item(t("Signature"), check_output($user->signature, 1));
+      }
+      break;
     case "edit_form":
       // when user tries to edit his own data
       return form_textarea(t("Signature"), "signature", $edit["signature"], 70, 3, t("Your signature will be publicly displayed at the end of your comments.") ."<br />". t("Allowed HTML tags") .": ". htmlspecialchars(variable_get("allowed_html", "<a> <b> <dd> <dl> <dt> <i> <li> <ol> <u> <ul>")));
diff --git a/modules/jabber.module b/modules/jabber.module
index 47be2babfd9381261e578ba0710b23598379b727..c69aa4463f6a1975e955ee9c16c4b807fd6c227b 100644
--- a/modules/jabber.module
+++ b/modules/jabber.module
@@ -168,7 +168,9 @@ function jabber_user($type, $edit, $user) {
   switch ($type) {
     case "view_private":
       $result = user_get_authname($user, $module);
-      $output .= form_item(t("$name ID"), $result);
+      if ($result) {
+        $output .= form_item(t("$name ID"), $result);
+      }
       return $output;
     case "edit_form":
       $result = user_get_authname($user, $module);