diff --git a/sys/fs/cd9660/cd9660_vnops.c b/sys/fs/cd9660/cd9660_vnops.c
--- a/sys/fs/cd9660/cd9660_vnops.c
+++ b/sys/fs/cd9660/cd9660_vnops.c
@@ -600,7 +600,8 @@
 		brelse (bp);
 
 	uio->uio_offset = idp->uio_off;
-	*ap->a_eofflag = idp->eofflag;
+	if (ap->a_eofflag != NULL)
+		*ap->a_eofflag = idp->eofflag;
 
 	free(idp, M_TEMP);
 
diff --git a/sys/fs/fuse/fuse_vnops.c b/sys/fs/fuse/fuse_vnops.c
--- a/sys/fs/fuse/fuse_vnops.c
+++ b/sys/fs/fuse/fuse_vnops.c
@@ -1944,7 +1944,7 @@
 	bool closefufh = false;
 	pid_t pid = curthread->td_proc->p_pid;
 
-	if (ap->a_eofflag)
+	if (ap->a_eofflag != NULL)
 		*ap->a_eofflag = 0;
 	if (fuse_isdeadfs(vp)) {
 		return (EXTERROR(ENXIO, "This FUSE session is about "
@@ -1997,7 +1997,7 @@
 			*ap->a_cookies = NULL;
 		}
 	}
-	if (err == 0 && tresid == uio->uio_resid)
+	if (err == 0 && tresid == uio->uio_resid && ap->a_eofflag != NULL)
 		*ap->a_eofflag = 1;
 
 	return err;
diff --git a/sys/fs/udf/udf_vnops.c b/sys/fs/udf/udf_vnops.c
--- a/sys/fs/udf/udf_vnops.c
+++ b/sys/fs/udf/udf_vnops.c
@@ -889,7 +889,8 @@
 	}
 
 	/* tell the calling layer whether we need to be called again */
-	*a->a_eofflag = uiodir.eofflag;
+	if (a->a_eofflag != NULL)
+		*a->a_eofflag = uiodir.eofflag;
 
 	if (error < 0)
 		error = 0;
diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c
--- a/sys/ufs/ufs/ufs_vnops.c
+++ b/sys/ufs/ufs/ufs_vnops.c
@@ -2407,7 +2407,8 @@
 		return (EINVAL);
 	ip = VTOI(vp);
 	if (ip->i_effnlink == 0) {
-		*ap->a_eofflag = 1;
+		if (ap->a_eofflag != NULL)
+			*ap->a_eofflag = 1;
 		return (0);
 	}
 	if (ap->a_ncookies != NULL) {
@@ -2512,7 +2513,7 @@
 			*ap->a_cookies = NULL;
 		}
 	}
-	if (error == 0 && ap->a_eofflag)
+	if (error == 0 && ap->a_eofflag != NULL)
 		*ap->a_eofflag = ip->i_size <= uio->uio_offset;
 	return (error);
 }