diff --git a/vfs/extfs.c b/vfs/extfs.c
index 3d4817fcb..0e0831e2f 100644
--- a/vfs/extfs.c
+++ b/vfs/extfs.c
@@ -90,7 +90,7 @@ struct archive {
 
 static struct entry *extfs_find_entry (struct entry *dir, char *name,
 				       int make_dirs, int make_file);
-static int extfs_which (struct vfs_class *me, char *path);
+static int extfs_which (struct vfs_class *me, const char *path);
 static void extfs_remove_entry (struct entry *e);
 static void extfs_free (vfsid id);
 
@@ -1302,7 +1302,7 @@ static int extfs_init (struct vfs_class *me)
 }
 
 /* Do NOT use me argument in this function */
-static int extfs_which (struct vfs_class *me, char *path)
+static int extfs_which (struct vfs_class *me, const char *path)
 {
     int i;
 
diff --git a/vfs/local.c b/vfs/local.c
index 7a7b5a9fc..c8fbb40a8 100644
--- a/vfs/local.c
+++ b/vfs/local.c
@@ -260,7 +260,7 @@ local_munmap (struct vfs_class *me, caddr_t addr, size_t len, void *data)
 #endif
 
 static int
-local_which (struct vfs_class *me, char *path)
+local_which (struct vfs_class *me, const char *path)
 {
     return 0;		/* Every path which other systems do not like is expected to be ours */
 }
diff --git a/vfs/sfs.c b/vfs/sfs.c
index b7583e27f..f5f8891c7 100644
--- a/vfs/sfs.c
+++ b/vfs/sfs.c
@@ -388,7 +388,7 @@ sfs_done (struct vfs_class *me)
 }
 
 static int
-sfs_which (struct vfs_class *me, char *path)
+sfs_which (struct vfs_class *me, const char *path)
 {
     int i;
 
diff --git a/vfs/vfs.h b/vfs/vfs.h
index 65ab6893c..18c9b2a9a 100644
--- a/vfs/vfs.h
+++ b/vfs/vfs.h
@@ -27,7 +27,7 @@ struct vfs_class {
     void (*done) (struct vfs_class *me);
     void (*fill_names) (struct vfs_class *me, fill_names_f);
 
-    int (*which) (struct vfs_class *me, /*FIXME:const*/ char *path);
+    int (*which) (struct vfs_class *me, const char *path);
 
     void *(*open) (struct vfs_class *me, const char *fname, int flags,
 		   int mode);