diff --git a/openfpga/src/fabric/build_top_module_connection.cpp b/openfpga/src/fabric/build_top_module_connection.cpp
index 2493c20c9..d5d4e7aea 100644
--- a/openfpga/src/fabric/build_top_module_connection.cpp
+++ b/openfpga/src/fabric/build_top_module_connection.cpp
@@ -753,17 +753,17 @@ static void add_top_module_nets_connect_sb_and_cb(
      * is_cb_exist() FOr RIGHT and BOTTOM side, find the adjacent RRGSB and then
      * use is_cb_exist()
      */
-    if (TOP == side_manager.get_side() || LEFT == side_manager.get_side()) {
+    if (BOTTOM == side_manager.get_side() || LEFT == side_manager.get_side()) {
       if (false == rr_gsb.is_cb_exist(cb_type)) {
         continue;
       }
     }
 
-    if (RIGHT == side_manager.get_side() || BOTTOM == side_manager.get_side()) {
+    if (RIGHT == side_manager.get_side() || TOP == side_manager.get_side()) {
       /* Only for the condition where cbs are on perimeter, the neighbour cb will be invalid
        * Bypass in such case on finding neighbour cbs
        */
-      if (BOTTOM == side_manager.get_side() && instance_sb_coordinate.y() == 0) {
+      if (TOP == side_manager.get_side() && instance_sb_coordinate.y() == device_rr_gsb.get_gsb_range().y()) {
         continue;
       }
       if (RIGHT == side_manager.get_side() && instance_sb_coordinate.x() == device_rr_gsb.get_gsb_range().x()) {
diff --git a/openfpga/src/fabric/build_top_module_utils.cpp b/openfpga/src/fabric/build_top_module_utils.cpp
index ebf52eb77..8b7c8f2e6 100644
--- a/openfpga/src/fabric/build_top_module_utils.cpp
+++ b/openfpga/src/fabric/build_top_module_utils.cpp
@@ -100,13 +100,13 @@ vtr::Point<size_t> find_top_module_gsb_coordinate_by_sb_side(
 
   vtr::Point<size_t> gsb_coordinate;
 
-  if ((TOP == sb_side) || (LEFT == sb_side)) {
+  if ((BOTTOM == sb_side) || (LEFT == sb_side)) {
     gsb_coordinate.set_x(rr_gsb.get_x());
     gsb_coordinate.set_y(rr_gsb.get_y());
     return gsb_coordinate;
   }
 
-  VTR_ASSERT((RIGHT == sb_side) || (BOTTOM == sb_side));
+  VTR_ASSERT((RIGHT == sb_side) || (TOP == sb_side));
 
   /* RIGHT side: x + 1 */
   if (RIGHT == sb_side) {
@@ -115,9 +115,9 @@ vtr::Point<size_t> find_top_module_gsb_coordinate_by_sb_side(
   }
 
   /* BOTTOM side: y - 1 */
-  if (BOTTOM == sb_side) {
+  if (TOP == sb_side) {
     gsb_coordinate.set_x(rr_gsb.get_x());
-    gsb_coordinate.set_y(rr_gsb.get_y() - 1);
+    gsb_coordinate.set_y(rr_gsb.get_y() + 1);
   }
 
   return gsb_coordinate;