diff --git a/src/fileio.c b/src/fileio.c
index f63bb60..bdc7439 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2981,6 +2981,13 @@
 
     if (fname == NULL || *fname == NUL)	/* safety check */
 	return FAIL;
+    if (buf->b_ml.ml_mfp == NULL)
+    {
+	/* This can happen during startup when there is a stray "w" in the
+	 * vimrc file. */
+	EMSG(_(e_emptybuf));
+	return FAIL;
+    }
 
     /*
      * Disallow writing from .exrc and .vimrc in current directory for