diff --git a/src/viewport.cpp b/src/viewport.cpp
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -1309,8 +1309,9 @@ static void ViewportAddSigns(DrawPixelIn
  * @param center the (preferred) center of the viewport sign
  * @param top    the new top of the sign
  * @param str    the string to show in the sign
+ * @param str_small the string to show when zoomed out. STR_NULL means same as \a str
  */
-void ViewportSign::UpdatePosition(int center, int top, StringID str)
+void ViewportSign::UpdatePosition(int center, int top, StringID str, StringID str_small)
 {
 	if (this->width_normal != 0) this->MarkDirty();
 
@@ -1323,6 +1324,9 @@ void ViewportSign::UpdatePosition(int ce
 	this->center = center;
 
 	/* zoomed out version */
+	if (str_small != STR_NULL) {
+		GetString(buffer, str_small, lastof(buffer));
+	}
 	this->width_small = VPSM_LEFT + Align(GetStringBoundingBox(buffer, FS_SMALL).width, 2) + VPSM_RIGHT;
 
 	this->MarkDirty();