diff --git a/sys/amd64/amd64/db_trace.c b/sys/amd64/amd64/db_trace.c
index 101ff39dbab6..dd6a93a12a6e 100644
--- a/sys/amd64/amd64/db_trace.c
+++ b/sys/amd64/amd64/db_trace.c
@@ -91,6 +91,7 @@ struct db_variable db_regs[] = {
 	{ "r15",	DB_OFFSET(tf_r15),	db_frame },
 	{ "rip",	DB_OFFSET(tf_rip),	db_frame },
 	{ "rflags",	DB_OFFSET(tf_rflags),	db_frame },
+#define	DB_N_SHOW_REGS	20	/* Don't show registers after here. */
 	{ "dr0",	NULL,			db_dr0 },
 	{ "dr1",	NULL,			db_dr1 },
 	{ "dr2",	NULL,			db_dr2 },
@@ -100,7 +101,7 @@ struct db_variable db_regs[] = {
 	{ "dr6",	NULL,			db_dr6 },
 	{ "dr7",	NULL,			db_dr7 },
 };
-struct db_variable *db_eregs = db_regs + sizeof(db_regs)/sizeof(db_regs[0]);
+struct db_variable *db_eregs = db_regs + DB_N_SHOW_REGS;
 
 #define DB_DRX_FUNC(reg)		\
 static int				\
diff --git a/sys/i386/i386/db_trace.c b/sys/i386/i386/db_trace.c
index c3ea8ac5c9d1..3bcb795fd14b 100644
--- a/sys/i386/i386/db_trace.c
+++ b/sys/i386/i386/db_trace.c
@@ -80,6 +80,7 @@ struct db_variable db_regs[] = {
 	{ "edi",	DB_OFFSET(tf_edi),	db_frame },
 	{ "eip",	DB_OFFSET(tf_eip),	db_frame },
 	{ "efl",	DB_OFFSET(tf_eflags),	db_frame },
+#define	DB_N_SHOW_REGS	15	/* Don't show registers after here. */
 	{ "dr0",	NULL,			db_dr0 },
 	{ "dr1",	NULL,			db_dr1 },
 	{ "dr2",	NULL,			db_dr2 },
@@ -89,7 +90,7 @@ struct db_variable db_regs[] = {
 	{ "dr6",	NULL,			db_dr6 },
 	{ "dr7",	NULL,			db_dr7 },
 };
-struct db_variable *db_eregs = db_regs + sizeof(db_regs)/sizeof(db_regs[0]);
+struct db_variable *db_eregs = db_regs + DB_N_SHOW_REGS;
 
 #define DB_DRX_FUNC(reg)		\
 static int				\