diff --git a/sysemu.h b/sysemu.h
index c7065ac038..ca25015390 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -176,7 +176,7 @@ extern TAILQ_HEAD(drivelist, DriveInfo) drives;
 extern TAILQ_HEAD(driveoptlist, DriveOpt) driveopts;
 
 extern DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
-extern DriveInfo *drive_get_by_id(char *id);
+extern DriveInfo *drive_get_by_id(const char *id);
 extern int drive_get_max_bus(BlockInterfaceType type);
 extern void drive_uninit(BlockDriverState *bdrv);
 extern const char *drive_get_serial(BlockDriverState *bdrv);
diff --git a/vl.c b/vl.c
index 6c4a509989..d82c3d84d2 100644
--- a/vl.c
+++ b/vl.c
@@ -1835,7 +1835,7 @@ DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit)
     return NULL;
 }
 
-DriveInfo *drive_get_by_id(char *id)
+DriveInfo *drive_get_by_id(const char *id)
 {
     DriveInfo *dinfo;