diff --git a/src/job.c b/src/job.c
index 892d237..884bf64 100644
--- a/src/job.c
+++ b/src/job.c
@@ -1582,7 +1582,7 @@
 /*
  * Return the effective prompt for the specified buffer.
  */
-    char_u *
+    static char_u *
 buf_prompt_text(buf_T* buf)
 {
     if (buf->b_prompt_text == NULL)