diff --git a/openair2/LAYER2/MAC/eNB_scheduler_RA.c b/openair2/LAYER2/MAC/eNB_scheduler_RA.c
index 64e8c8380f..88ee3d14ae 100755
--- a/openair2/LAYER2/MAC/eNB_scheduler_RA.c
+++ b/openair2/LAYER2/MAC/eNB_scheduler_RA.c
@@ -209,7 +209,7 @@ void generate_Msg2(module_id_t module_idP,int CC_idP,frame_t frameP,sub_frame_t
     // get narrowband according to higher-layer config 
     num_nb = p[RA_template->rach_resource_type-1]->mpdcch_NarrowbandsToMonitor_r13.list.count;
     RA_template->msg2_narrowband = *p[RA_template->rach_resource_type-1]->mpdcch_NarrowbandsToMonitor_r13.list.array[RA_template->preamble_index%num_nb];
-    first_rb = RA_template->msg2_narrowband*6;
+    first_rb = narrowband_to_first_rb(&cc[CC_idP],RA_template->msg2_narrowband);
     
     if ((RA_template->msg2_mpdcch_repetition_cnt == 0) &&
 	(mpdcch_sf_condition(eNB,CC_idP,frameP,subframeP,rmax,TYPE2)>0)){
@@ -555,8 +555,8 @@ void generate_Msg4(module_id_t module_idP,int CC_idP,frame_t frameP,sub_frame_t
     // get actual repetition count from Table 9.1.5-3
     reps           = (rmax<=8)?(1<<rep):(rmax>>(3-rep));
     // get first narrowband
-    first_rb = RA_template->msg34_narrowband*6;
-    
+    first_rb = narrowband_to_first_rb(&cc[CC_idP],RA_template->msg34_narrowband);
+
     if ((RA_template->msg4_mpdcch_repetition_cnt == 0) &&
 	(mpdcch_sf_condition(eNB,CC_idP,frameP,subframeP,rmax,TYPE2)>0)){
       // MPDCCH configuration for RAR
diff --git a/openair2/LAYER2/MAC/eNB_scheduler_bch.c b/openair2/LAYER2/MAC/eNB_scheduler_bch.c
index 1cace89799..4e4c8aca1f 100755
--- a/openair2/LAYER2/MAC/eNB_scheduler_bch.c
+++ b/openair2/LAYER2/MAC/eNB_scheduler_bch.c
@@ -199,8 +199,10 @@ schedule_SIB1_BR(
     if ((frameP&1023) < 200) LOG_I(MAC,"[eNB %d] Frame %d Subframe %d: SIB1_BR->DLSCH CC_id %d, Received %d bytes, scheduling on NB %d (i %d,m %d,N_S_NB %d)  rvidx %d\n",module_idP,frameP,subframeP,CC_id,bcch_sdu_length,n_NB,i,m,N_S_NB,rvidx);
     
     // allocate all 6 PRBs in narrowband for SIB1_BR
-    first_rb = n_NB*6;
-    vrb_map[first_rb]   = 1;
+
+    first_rb = narrowband_to_first_rb(cc,n_NB);
+
+    vrb_map[first_rb] = 1;
     vrb_map[first_rb+1] = 1;
     vrb_map[first_rb+2] = 1;
     vrb_map[first_rb+3] = 1;
@@ -385,11 +387,11 @@ schedule_SI_BR(
 			bcch_sdu_length,(int)(si_TBS_r13>>3),(int)schedulingInfoList_BR_r13->list.array[i]->si_TBS_r13);
 
 	    // allocate all 6 PRBs in narrowband for SIB1_BR
-	    first_rb = (si_Narrowband_r13-1)*6;
 
 	    // check that SIB1 didn't take this narrowband
 	    if (vrb_map[first_rb] > 0) continue;
 
+	    first_rb = narrowband_to_first_rb(cc,si_Narrowband_r13);
 	    vrb_map[first_rb]   = 1;
 	    vrb_map[first_rb+1] = 1;
 	    vrb_map[first_rb+2] = 1;
diff --git a/openair2/LAYER2/MAC/eNB_scheduler_primitives.c b/openair2/LAYER2/MAC/eNB_scheduler_primitives.c
index 52ff9a45a0..9fa7c16868 100755
--- a/openair2/LAYER2/MAC/eNB_scheduler_primitives.c
+++ b/openair2/LAYER2/MAC/eNB_scheduler_primitives.c
@@ -524,7 +524,35 @@ int mpdcch_sf_condition(eNB_MAC_INST *eNB,int CC_id, frame_t frameP,sub_frame_t
 
 }
 
+int narrowband_to_first_rb(COMMON_channels_t *cc, int nb_index) {
 
+  switch (cc->mib->message.dl_Bandwidth) {
+  case 0: // 6 PRBs, N_NB=1, i_0=0
+    return(0);
+    break;
+  case 3: // 50 PRBs, N_NB=8, i_0=1
+    return((int)(1+(6*nb_index)));
+    break;
+  case 5: // 100 PRBs, N_NB=16, i_0=2
+    return((int)(2+(6*nb_index)));
+    break;
+  case 1: // 15 PRBs  N_NB=2, i_0=1
+    if (nb_index>0) return(1);
+    else            return(0);
+    break;
+  case 2: // 25 PRBs, N_NB=4, i_0=0
+    if (nb_index>1) return(1+(6*nb_index));
+    else            return((6*nb_index));
+    break;
+  case 4: // 75 PRBs, N_NB=12, i_0=1
+    if (nb_index>5) return(2+(6*nb_index));
+    else            return(1+(6*nb_index));
+    break;
+  default:
+    AssertFatal(1==0,"Impossible dl_Bandwidth %d\n",cc->mib->message.dl_Bandwidth);
+    break;
+  }
+}
 #endif
 
 //------------------------------------------------------------------------------
diff --git a/openair2/LAYER2/MAC/proto.h b/openair2/LAYER2/MAC/proto.h
index f25a148d26..1a7421c7e7 100755
--- a/openair2/LAYER2/MAC/proto.h
+++ b/openair2/LAYER2/MAC/proto.h
@@ -908,6 +908,9 @@ int get_numnarrowbandbits(long dl_Bandwidth);
 int mpdcch_sf_condition(eNB_MAC_INST *eNB,int CC_id, frame_t frameP,sub_frame_t subframeP,int rmax,MPDCCH_TYPES_t mpdcch_type);
 
 int get_numnarrowbands(long dl_Bandwidth);
+
+int narrowband_to_first_rb(COMMON_channels_t *cc, int nb_index);
+
 #endif