diff --git a/src/memline.c b/src/memline.c
index 2cdd227..83344bc 100644
--- a/src/memline.c
+++ b/src/memline.c
@@ -3361,7 +3361,8 @@
 }
 
 
-#if defined(FEAT_SPELL) || defined(FEAT_QUICKFIX) || defined(PROTO)
+#if defined(FEAT_SPELL) || defined(FEAT_QUICKFIX) || defined(FEAT_PROP_POPUP) \
+	|| defined(PROTO)
 /*
  * Like ml_append() but for an arbitrary buffer.  The buffer must already have
  * a memline.