diff --git a/src/undo.c b/src/undo.c
index 259de9a..c2fe819 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -375,6 +375,7 @@
     return ul->ul_line == NULL ? FAIL : OK;
 }
 
+#ifdef FEAT_PROP_POPUP
 /*
  * return TRUE if line "lnum" has text property "flags".
  */
@@ -395,6 +396,7 @@
     }
     return FALSE;
 }
+#endif
 
 /*
  * Common code for various ways to save text before a change.