diff --git a/sys/gnu/i386/isa/sound/awe_wave.c b/sys/gnu/i386/isa/sound/awe_wave.c
index 1f3269e1625..c4f3cbf3fe6 100644
--- a/sys/gnu/i386/isa/sound/awe_wave.c
+++ b/sys/gnu/i386/isa/sound/awe_wave.c
@@ -21,6 +21,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include <stddef.h>
+
 #ifdef __FreeBSD__
 #  include <gnu/i386/isa/sound/awe_config.h>
 #else
@@ -3296,7 +3298,7 @@ awe_load_guspatch(const char *addr, int offs, int size, int pmgr_flag)
 	int note, free_sample, free_info;
 	int rc;
 
-	sizeof_patch = (int)((long)&patch.data[0] - (long)&patch); /* header size */
+	sizeof_patch = offsetof(struct patch_info, data); /* header size */
 	if (size < sizeof_patch) {
 		printk("AWE32 Error: Patch header too short\n");
 		return RET_ERROR(EINVAL);
diff --git a/sys/i386/isa/sound/gus_wave.c b/sys/i386/isa/sound/gus_wave.c
index 55463c933a3..9b3ab0b48b4 100644
--- a/sys/i386/isa/sound/gus_wave.c
+++ b/sys/i386/isa/sound/gus_wave.c
@@ -27,6 +27,8 @@
  * 
  */
 
+#include <stddef.h>
+
 #include <i386/isa/sound/sound_config.h>
 #include <i386/isa/sound/ultrasound.h>
 #include <i386/isa/sound/gus_hw.h>
@@ -1569,7 +1571,7 @@ guswave_load_patch(int dev, int format, snd_rw_buf * addr,
 
     u_long   blk_size, blk_end, left, src_offs, target;
 
-    sizeof_patch = (long) &patch.data[0] - (long) &patch; /* Header size */
+    sizeof_patch = offsetof(struct patch_info, data); /* Header size */
 
     if (format != GUS_PATCH) {
 	printf("GUS Error: Invalid patch format (key) 0x%x\n", format);
diff --git a/sys/i386/isa/sound/midi_synth.c b/sys/i386/isa/sound/midi_synth.c
index 86032e3db16..e63b24ad863 100644
--- a/sys/i386/isa/sound/midi_synth.c
+++ b/sys/i386/isa/sound/midi_synth.c
@@ -30,6 +30,8 @@
 #define USE_SEQ_MACROS
 #define USE_SIMPLE_MACROS
 
+#include <stddef.h>
+
 #include <i386/isa/sound/sound_config.h>
 
 #if defined(CONFIGURE_SOUNDCARD) /* && defined(CONFIG_MIDI) */
@@ -448,7 +450,7 @@ midi_synth_load_patch(int dev, int format, snd_rw_buf * addr,
     int             i;
     unsigned long   left, src_offs, eox_seen = 0;
     int             first_byte = 1;
-    int             hdr_size = (unsigned long) &sysex.data[0] - (unsigned long) &sysex;
+    int             hdr_size = offsetof(struct sysex_info, data);
 
     leave_sysex(dev);