diff --git a/cpu/mpc83xx/cpu_init.c b/cpu/mpc83xx/cpu_init.c
index fb184d8..67c9e57 100644
--- a/cpu/mpc83xx/cpu_init.c
+++ b/cpu/mpc83xx/cpu_init.c
@@ -181,8 +181,13 @@
 
 	/* System General Purpose Register */
 #ifdef CFG_SICRH
+#if defined(CONFIG_MPC834X) || defined(CONFIG_MPC8313)
+	/* regarding to MPC34x manual rev.1 bits 28..29 must be preserved */
+	im->sysconf.sicrh = (im->sysconf.sicrh & 0x0000000C) | CFG_SICRH;
+#else
 	im->sysconf.sicrh = CFG_SICRH;
 #endif
+#endif
 #ifdef CFG_SICRL
 	im->sysconf.sicrl = CFG_SICRL;
 #endif