diff --git a/src/com/xilinx/rapidwright/design/ModuleInst.java b/src/com/xilinx/rapidwright/design/ModuleInst.java
index b615bff55..5130573dc 100644
--- a/src/com/xilinx/rapidwright/design/ModuleInst.java
+++ b/src/com/xilinx/rapidwright/design/ModuleInst.java
@@ -39,9 +39,6 @@
 import com.xilinx.rapidwright.device.Site;
 import com.xilinx.rapidwright.device.SiteTypeEnum;
 import com.xilinx.rapidwright.device.Tile;
-import com.xilinx.rapidwright.edif.EDIFNet;
-import com.xilinx.rapidwright.edif.EDIFPortInst;
-import com.xilinx.rapidwright.edif.EDIFTools;
 import com.xilinx.rapidwright.util.MessageGenerator;
 import com.xilinx.rapidwright.util.Utils;
 
@@ -356,6 +353,10 @@ public boolean place(Site newAnchorSite, boolean skipIncompatible, boolean allow
                         }
                     }
                 }
+                if (existingSiteInst != null) {
+                    unplace();
+                    return false;
+                }
             }
 
             if (newSite == null || existingSiteInst != null) {