diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c
index 76a3637b88e0ac90338296638ac9215ae2d3272e..f16bd04e39e9566dabe8928e7cd526bdcd26010c 100644
--- a/arch/s390/mm/cmm.c
+++ b/arch/s390/mm/cmm.c
@@ -374,7 +374,7 @@ static struct ctl_table cmm_dir_table[] = {
 #ifdef CONFIG_CMM_IUCV
 #define SMSG_PREFIX "CMM"
 static void
-cmm_smsg_target(char *from, char *msg)
+cmm_smsg_target(const char *from, char *msg)
 {
 	long nr, seconds;
 
diff --git a/drivers/s390/net/smsgiucv.c b/drivers/s390/net/smsgiucv.c
index 67f2485d2372512376c770031aac583201ad27d9..3e666b6e77b4e799cbce6ca6424f2ee87842c431 100644
--- a/drivers/s390/net/smsgiucv.c
+++ b/drivers/s390/net/smsgiucv.c
@@ -31,9 +31,9 @@
 
 struct smsg_callback {
 	struct list_head list;
-	char *prefix;
+	const char *prefix;
 	int len;
-	void (*callback)(char *from, char *str);
+	void (*callback)(const char *from, char *str);
 };
 
 MODULE_AUTHOR
@@ -100,8 +100,8 @@ static void smsg_message_pending(struct iucv_path *path,
 	kfree(buffer);
 }
 
-int smsg_register_callback(char *prefix,
-			   void (*callback)(char *from, char *str))
+int smsg_register_callback(const char *prefix,
+			   void (*callback)(const char *from, char *str))
 {
 	struct smsg_callback *cb;
 
@@ -117,8 +117,9 @@ int smsg_register_callback(char *prefix,
 	return 0;
 }
 
-void smsg_unregister_callback(char *prefix,
-			      void (*callback)(char *from, char *str))
+void smsg_unregister_callback(const char *prefix,
+			      void (*callback)(const char *from,
+					       char *str))
 {
 	struct smsg_callback *cb, *tmp;
 
diff --git a/drivers/s390/net/smsgiucv.h b/drivers/s390/net/smsgiucv.h
index 67f5d4f8378d2c54f90c25ccde6fa0107bf040a8..9410b45fde03efe5df14045d6e619a9d78196220 100644
--- a/drivers/s390/net/smsgiucv.h
+++ b/drivers/s390/net/smsgiucv.h
@@ -5,6 +5,8 @@
  * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
  */
 
-int  smsg_register_callback(char *, void (*)(char *, char *));
-void smsg_unregister_callback(char *, void (*)(char *, char *));
+int  smsg_register_callback(const char *,
+			    void (*)(const char *, char *));
+void smsg_unregister_callback(const char *,
+			      void (*)(const char *, char *));