diff --git a/apps/machine/electron/main.ts b/apps/machine/electron/main.ts
index 51f8bbe..1b6c41e 100644
--- a/apps/machine/electron/main.ts
+++ b/apps/machine/electron/main.ts
@@ -248,22 +248,25 @@ ipcMain.handle('hal:disable-validator', () => {
 })
 
 ipcMain.handle('hal:stack-bill', () => {
-  if (halInstance) {
-    const denomination = pendingBillDenomination
-    pendingBillDenomination = null
-    halInstance.stackBill()
-    // Notify renderer that the bill was accepted
-    if (denomination !== null) {
-      mainWindow?.webContents.send('hal:bill-inserted', denomination)
-    }
+  if (!halInstance) return
+  if (pendingBillDenomination === null) {
+    console.warn('[Electron] hal:stack-bill called with no bill in escrow — ignoring')
+    return
   }
+  const denomination = pendingBillDenomination
+  pendingBillDenomination = null
+  halInstance.stackBill()
+  mainWindow?.webContents.send('hal:bill-inserted', denomination)
 })
 
 ipcMain.handle('hal:reject-bill', () => {
-  if (halInstance) {
-    pendingBillDenomination = null
-    halInstance.rejectBill()
+  if (!halInstance) return
+  if (pendingBillDenomination === null) {
+    console.warn('[Electron] hal:reject-bill called with no bill in escrow — ignoring')
+    return
   }
+  pendingBillDenomination = null
+  halInstance.rejectBill()
 })
 
 ipcMain.handle('hal:get-inventory', () => {