diff --git a/block/dmg.c b/block/dmg.c
index e10b9a2ba5..2769900359 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -31,11 +31,8 @@
 #include "qemu/memalign.h"
 #include "dmg.h"
 
-int (*dmg_uncompress_bz2)(char *next_in, unsigned int avail_in,
-                          char *next_out, unsigned int avail_out);
-
-int (*dmg_uncompress_lzfse)(char *next_in, unsigned int avail_in,
-                            char *next_out, unsigned int avail_out);
+BdrvDmgUncompressFunc *dmg_uncompress_bz2;
+BdrvDmgUncompressFunc *dmg_uncompress_lzfse;
 
 enum {
     /* Limit chunk sizes to prevent unreasonable amounts of memory being used
diff --git a/block/dmg.h b/block/dmg.h
index e488601b62..dcd6165e63 100644
--- a/block/dmg.h
+++ b/block/dmg.h
@@ -51,10 +51,10 @@ typedef struct BDRVDMGState {
     z_stream zstream;
 } BDRVDMGState;
 
-extern int (*dmg_uncompress_bz2)(char *next_in, unsigned int avail_in,
-                                 char *next_out, unsigned int avail_out);
+typedef int BdrvDmgUncompressFunc(char *next_in, unsigned int avail_in,
+                                  char *next_out, unsigned int avail_out);
 
-extern int (*dmg_uncompress_lzfse)(char *next_in, unsigned int avail_in,
-                                   char *next_out, unsigned int avail_out);
+extern BdrvDmgUncompressFunc *dmg_uncompress_bz2;
+extern BdrvDmgUncompressFunc *dmg_uncompress_lzfse;
 
 #endif