diff --git a/himbaechel/uarch/ng-ultra/ng_ultra.cc b/himbaechel/uarch/ng-ultra/ng_ultra.cc
index be084724..4e91199e 100644
--- a/himbaechel/uarch/ng-ultra/ng_ultra.cc
+++ b/himbaechel/uarch/ng-ultra/ng_ultra.cc
@@ -585,12 +585,10 @@ bool NgUltraImpl::isBelLocationValid(BelId bel, bool explain_invalid) const
 // Bel bucket functions
 IdString NgUltraImpl::getBelBucketForCellType(IdString cell_type) const
 {
-    if (cell_type.in(id_IOP,id_IP,id_OP))
-        return id_IOP;
-    else if (cell_type.in(id_IOTP,id_ITP,id_OTP))
-        return id_IOTP;
-    else if (cell_type.in(id_BFR))
-        return id_DFR;
+    if (cell_type.in(id_IOP,id_IP,id_OP,id_IOTP,id_ITP,id_OTP))
+        return ctx->idf("IOP/IOTP");
+    else if (cell_type.in(id_BFR, id_DFR, id_DDFR))
+        return ctx->idf("DFR/DDFR");
     else if (cell_type.in(id_RF, id_RFSP))
         return id_RF;
     else if (cell_type.in(id_XHRF, id_XWRF, id_XPRF))
@@ -609,6 +607,16 @@ IdString NgUltraImpl::getBelBucketForCellType(IdString cell_type) const
         return cell_type;
 }
 
+BelBucketId NgUltraImpl::getBelBucketForBel(BelId bel) const
+{
+    IdString bel_type = ctx->getBelType(bel);
+    if (bel_type.in(id_IOP, id_IOTP))
+        return ctx->idf("IOP/IOTP");
+    else if (bel_type.in(id_DFR, id_DDFR))
+        return ctx->idf("DFR/DDFR");
+    return bel_type;
+}
+
 bool NgUltraImpl::isValidBelForCellType(IdString cell_type, BelId bel) const
 {
     IdString bel_type = ctx->getBelType(bel);
diff --git a/himbaechel/uarch/ng-ultra/ng_ultra.h b/himbaechel/uarch/ng-ultra/ng_ultra.h
index 3b9df650..403efe9a 100644
--- a/himbaechel/uarch/ng-ultra/ng_ultra.h
+++ b/himbaechel/uarch/ng-ultra/ng_ultra.h
@@ -48,6 +48,7 @@ struct NgUltraImpl : HimbaechelAPI
     bool isBelLocationValid(BelId bel, bool explain_invalid = false) const override;
     IdString getBelBucketForCellType(IdString cell_type) const override;
     bool isValidBelForCellType(IdString cell_type, BelId bel) const override;
+    BelBucketId getBelBucketForBel(BelId bel) const override;
 
     // Flow management
     void pack() override;
diff --git a/himbaechel/uarch/ng-ultra/pack.cc b/himbaechel/uarch/ng-ultra/pack.cc
index da2f367e..29aaf864 100644
--- a/himbaechel/uarch/ng-ultra/pack.cc
+++ b/himbaechel/uarch/ng-ultra/pack.cc
@@ -738,7 +738,7 @@ void NgUltraPacker::pack_iobs(void)
         }
         ci.type = new_type;
         ctx->bindBel(bel, &ci, PlaceStrength::STRENGTH_LOCKED);
-        if (!ctx->isValidBelForCellType(ctx->getBelBucketForCellType(new_type),bel))
+        if (!ctx->isValidBelForCellType(new_type,bel))
             log_error("Invalid type of IO for specified location %s %s.\n", new_type.c_str(ctx), ctx->getBelType(bel).c_str(ctx));
         to_update.push_back(&ci);
     }