diff --git a/ChangeLog b/ChangeLog
index a760e1d0b..ab597d477 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -44,7 +44,9 @@ http://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 * aspell: fix detection of nicks with non-alphanumeric chars
 * guile: disable guile gmp allocator (fix crash on unload of relay plugin)
   (bug #40628)
-* irc: use color code 0x16 (ctrl-V) for reverse video in messages
+* irc: use color code 0x1F (`ctrl-_`) for underlined text in input line (same
+  code as messages) (bug #40756)
+* irc: use color code 0x16 (`ctrl-V`) for reverse video in messages
 * irc: use option irc.network.colors_send instead of irc.network.colors_receive
   when displaying messages sent by commands /away, /me, /msg, /notice, /query
 * irc: fix memory leak when checking the value of ssl_priorities option in
diff --git a/src/plugins/irc/irc-color.c b/src/plugins/irc/irc-color.c
index 08b57f0f9..c19199f97 100644
--- a/src/plugins/irc/irc-color.c
+++ b/src/plugins/irc/irc-color.c
@@ -308,7 +308,7 @@ irc_color_decode_for_user_entry (const char *string)
                 ptr_string++;
                 break;
             case IRC_COLOR_UNDERLINE_CHAR:
-                out[out_pos++] = 0x15;
+                out[out_pos++] = 0x1F;
                 ptr_string++;
                 break;
             case IRC_COLOR_COLOR_CHAR:
@@ -404,16 +404,16 @@ irc_color_encode (const char *string, int keep_colors)
                     out[out_pos++] = IRC_COLOR_RESET_CHAR;
                 ptr_string++;
                 break;
-            case 0x15: /* ^U */
-                if (keep_colors)
-                    out[out_pos++] = IRC_COLOR_UNDERLINE_CHAR;
-                ptr_string++;
-                break;
             case 0x16: /* ^V */
                 if (keep_colors)
                     out[out_pos++] = IRC_COLOR_REVERSE_CHAR;
                 ptr_string++;
                 break;
+            case 0x1F: /* ^_ */
+                if (keep_colors)
+                    out[out_pos++] = IRC_COLOR_UNDERLINE_CHAR;
+                ptr_string++;
+                break;
             default:
                 length = weechat_utf8_char_size ((char *)ptr_string);
                 if (length == 0)