diff --git a/common/placer_heap.cc b/common/placer_heap.cc
index 27144316..f8385cef 100644
--- a/common/placer_heap.cc
+++ b/common/placer_heap.cc
@@ -402,13 +402,6 @@ class HeAPPlacer
         for (auto &cell_entry : ctx->cells) {
             CellInfo *cell = cell_entry.second.get();
 
-            if (cell->bel != BelId()) {
-                if (ctx->verbose)
-                    log_error("Cell \'%s\' (%s) has already been constrianed by arch implementation",
-                              cell->name.c_str(ctx), cell->type.c_str(ctx));
-                continue;
-            }
-
             auto loc = cell->attrs.find(ctx->id("BEL"));
             if (loc != cell->attrs.end()) {
                 std::string loc_name = loc->second.as_string();
diff --git a/fpga_interchange/arch_place_constr.cc b/fpga_interchange/arch_place_constr.cc
index 2a3118bd..3af48656 100644
--- a/fpga_interchange/arch_place_constr.cc
+++ b/fpga_interchange/arch_place_constr.cc
@@ -83,11 +83,8 @@ void Arch::place_constraints()
                       cell->name.c_str(getCtx()), nameOfBel(bel), bound_cell->name.c_str(getCtx()));
 
         bindBel(bel, cell, STRENGTH_USER);
-        if (!isBelLocationValid(bel))
-            log_error("Bel \'%s\' is not valid for cell "
-                      "\'%s\' of type \'%s\'\n",
-                      nameOfBel(bel), cell->name.c_str(getCtx()), cell->type.c_str(getCtx()));
 
+        cell->attrs.erase(id("BEL"));
         constrained_cells.emplace_back(cell->name, bel);
     }
 
@@ -95,8 +92,15 @@ void Arch::place_constraints()
         return;
 
     log_info("Cell placed via user constraints:\n");
-    for (auto cell_bel : constrained_cells)
-        log_info("  - %s placed at %s\n", cell_bel.first.c_str(getCtx()), nameOfBel(cell_bel.second));
+    for (auto cell_bel : constrained_cells) {
+        IdString cell_name = cell_bel.first;
+        BelId bel = cell_bel.second;
+
+        if (!isBelLocationValid(bel))
+            log_error("  - Bel \'%s\' is not valid for cell \'%s\'\n", nameOfBel(bel), cell_name.c_str(getCtx()));
+
+        log_info("  - %s placed at %s\n", cell_name.c_str(getCtx()), nameOfBel(cell_bel.second));
+    }
 }
 
 NEXTPNR_NAMESPACE_END
diff --git a/fpga_interchange/xdc.cc b/fpga_interchange/xdc.cc
index 17a2ed3e..9085615b 100644
--- a/fpga_interchange/xdc.cc
+++ b/fpga_interchange/xdc.cc
@@ -130,15 +130,8 @@ static int get_cells(ClientData data, Tcl_Interp *interp, int objc, Tcl_Obj *CON
         const char *arg0 = Tcl_GetString(objv[1]);
         IdString cell_name = ctx->id(arg0);
 
-        CellInfo *cell = nullptr;
-        for (auto &cell_pair : ctx->cells) {
-            if (cell_pair.second.get()->name == cell_name) {
-                cell = cell_pair.second.get();
-                break;
-            }
-        }
-
-        if (cell == nullptr) {
+        auto iter = ctx->cells.find(cell_name);
+        if (iter == ctx->cells.end()) {
             Tcl_SetStringResult(interp, "Could not find cell " + cell_name.str(ctx));
             return TCL_ERROR;
         }
@@ -146,7 +139,7 @@ static int get_cells(ClientData data, Tcl_Interp *interp, int objc, Tcl_Obj *CON
         Tcl_Obj *result = Tcl_NewObj();
         result->typePtr = &cell_object;
         result->internalRep.twoPtrValue.ptr1 = (void *)(ctx);
-        result->internalRep.twoPtrValue.ptr2 = (void *)(cell);
+        result->internalRep.twoPtrValue.ptr2 = (void *)(iter->second.get());
 
         result->bytes = nullptr;
         cell_update_string(result);