diff --git a/client/src/components/rack/ModuleBlock.tsx b/client/src/components/rack/ModuleBlock.tsx
index 7dbfd69..30473a8 100644
--- a/client/src/components/rack/ModuleBlock.tsx
+++ b/client/src/components/rack/ModuleBlock.tsx
@@ -49,15 +49,20 @@ export function ModuleBlock({ module }: ModuleBlockProps) {
 
   // Split Main ports into rows
   const portRows: (typeof module.ports)[] = [];
-  for (let i = 0; i < mainPorts.length; i += PORTS_PER_ROW) {
-    portRows.push(mainPorts.slice(i, i + PORTS_PER_ROW));
+  if (mainPorts.length > 0) {
+    for (let i = 0; i < mainPorts.length; i += PORTS_PER_ROW) {
+      portRows.push(mainPorts.slice(i, i + PORTS_PER_ROW));
+    }
+  } else if (sidePorts.length > 0) {
+    // If only special ports exist, create an empty first row to hold them
+    portRows.push([]);
   }
   
   // Calculate vertical space
   const availableForPorts = height - 16;
   const maxRows = Math.max(1, Math.floor(availableForPorts / 14));
-  const visibleRows = portRows.slice(0, maxRows);
-  const hiddenPortCount = mainPorts.length - visibleRows.flat().length;
+  const visibleRows = portRows.length > 0 ? portRows.slice(0, maxRows) : [];
+  const hiddenPortCount = mainPorts.length - (visibleRows.length > 0 ? visibleRows.flat().length : 0);
 
   // SFP/WAN ports often sit on the far right of the module
   // We'll show them on the first row if possible