diff --git a/src/include/cbfs.h b/src/include/cbfs.h
index b89a13d..37bac30 100644
--- a/src/include/cbfs.h
+++ b/src/include/cbfs.h
@@ -67,7 +67,7 @@
  * attributes). Must return a pointer to space of the requested size where the file data should
  * be loaded, or NULL to make the operation fail.
  */
-typedef void *(*cbfs_allocator_t)(void *arg, size_t size, union cbfs_mdata *mdata);
+typedef void *(*cbfs_allocator_t)(void *arg, size_t size, const union cbfs_mdata *mdata);
 
 static inline size_t cbfs_load(const char *name, void *buf, size_t size);
 static inline size_t cbfs_ro_load(const char *name, void *buf, size_t size);
@@ -183,9 +183,9 @@
 	void *buf;
 	size_t buf_size;
 };
-void *_cbfs_default_allocator(void *arg, size_t size, union cbfs_mdata *unused);
+void *_cbfs_default_allocator(void *arg, size_t size, const union cbfs_mdata *unused);
 
-void *_cbfs_cbmem_allocator(void *arg, size_t size, union cbfs_mdata *unused);
+void *_cbfs_cbmem_allocator(void *arg, size_t size, const union cbfs_mdata *unused);
 
 /**********************************************************************************************
  *                                  INLINE IMPLEMENTATIONS                                    *
diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index fbf4531..65bb721 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -369,7 +369,7 @@
 	return loc;
 }
 
-void *_cbfs_default_allocator(void *arg, size_t size, union cbfs_mdata *unused)
+void *_cbfs_default_allocator(void *arg, size_t size, const union cbfs_mdata *unused)
 {
 	struct _cbfs_default_allocator_arg *darg = arg;
 	if (size > darg->buf_size)
@@ -377,7 +377,7 @@
 	return darg->buf;
 }
 
-void *_cbfs_cbmem_allocator(void *arg, size_t size, union cbfs_mdata *unused)
+void *_cbfs_cbmem_allocator(void *arg, size_t size, const union cbfs_mdata *unused)
 {
 	return cbmem_add((uintptr_t)arg, size);
 }
diff --git a/src/lib/rmodule.c b/src/lib/rmodule.c
index ac9eb0b..31bf141 100644
--- a/src/lib/rmodule.c
+++ b/src/lib/rmodule.c
@@ -192,7 +192,7 @@
 }
 
 static void *rmodule_cbfs_allocator(void *rsl_arg, size_t unused,
-				    union cbfs_mdata *mdata)
+				    const union cbfs_mdata *mdata)
 {
 	struct rmod_stage_load *rsl = rsl_arg;