diff --git a/openbsc/src/abis_rsl.c b/openbsc/src/abis_rsl.c
index f387354..e47900d 100644
--- a/openbsc/src/abis_rsl.c
+++ b/openbsc/src/abis_rsl.c
@@ -1203,7 +1203,10 @@
 	if (!lchan->ts->hopping.enabled) {
 		ia.mob_alloc_len = 0;
 	} else {
-		/* FIXME: Mobile Allocation in case of hopping */
+		uint8_t *ma;
+		ia.mob_alloc_len = lchan->ts->hopping.ma_len;
+		ma = msgb_put(msg, ia.mob_alloc_len);
+		memcpy(ma, lchan->ts->hopping.ma_data, ia.mob_alloc_len);
 	}
 
 	DEBUGP(DRSL, "%s Activating ARFCN(%u) SS(%u) lctype %s "