diff --git a/zipl/boot/sclp.c b/zipl/boot/sclp.c
index 0326a327..ad6019a3 100644
--- a/zipl/boot/sclp.c
+++ b/zipl/boot/sclp.c
@@ -126,20 +126,20 @@ int sclp_setup(int initialise)
 
 	switch (initialise) {
 	case SCLP_INIT:
-		sccb->receive_mask = 0x80000000;
-		sccb->send_mask = 0x40000000;
+		sccb->receive_mask = SCLP_EVENT_MASK_OPCMD;
+		sccb->send_mask = SCLP_EVENT_MASK_MSG;
 		break;
 	case SCLP_DISABLE:
-		sccb->receive_mask = 0x0;
-		sccb->send_mask = 0x0;
+		sccb->receive_mask = SCLP_EVENT_MASK_DISABLE;
+		sccb->send_mask = SCLP_EVENT_MASK_DISABLE;
 		break;
 	case SCLP_HSA_INIT:
-		sccb->receive_mask = 0x0;
-		sccb->send_mask = 0x40000010;
+		sccb->receive_mask = SCLP_EVENT_MASK_DISABLE;
+		sccb->send_mask = SCLP_EVENT_MASK_MSG | SCLP_EVENT_MASK_SDIAS;
 		break;
 	case SCLP_HSA_INIT_ASYNC:
-		sccb->receive_mask = 0x00000010;
-		sccb->send_mask = 0x40000010;
+		sccb->receive_mask = SCLP_EVENT_MASK_SDIAS;
+		sccb->send_mask = SCLP_EVENT_MASK_MSG | SCLP_EVENT_MASK_SDIAS;
 		break;
 	}
 
diff --git a/zipl/boot/sclp.h b/zipl/boot/sclp.h
index 1c8c7139..fa94fd5a 100644
--- a/zipl/boot/sclp.h
+++ b/zipl/boot/sclp.h
@@ -28,6 +28,12 @@
 #define SCLP_CMD_READ_INFO2     0x00020001
 #define SCLP_CMD_READ_DATA      0x00770005
 
+/* SCLP event masks */
+#define SCLP_EVENT_MASK_DISABLE	0x00000000
+#define SCLP_EVENT_MASK_SDIAS	0x00000010
+#define SCLP_EVENT_MASK_MSG	0x40000000
+#define SCLP_EVENT_MASK_OPCMD	0x80000000
+
 #define PSW_EXT_MASK            0x00080000ULL
 #define PSW_EXT_ADDR            0x80000000ULL
 #define PSW_WAIT_MASK           0x010a0000ULL