diff --git a/src/include/ipxe/efi/efi_pci.h b/src/include/ipxe/efi/efi_pci_api.h
similarity index 95%
rename from src/include/ipxe/efi/efi_pci.h
rename to src/include/ipxe/efi/efi_pci_api.h
index e06473d3..1bc43e30 100644
--- a/src/include/ipxe/efi/efi_pci.h
+++ b/src/include/ipxe/efi/efi_pci_api.h
@@ -1,5 +1,5 @@
-#ifndef _IPXE_EFI_PCI_H
-#define _IPXE_EFI_PCI_H
+#ifndef _IPXE_EFI_PCI_API_H
+#define _IPXE_EFI_PCI_API_H
 
 /** @file
  *
@@ -39,8 +39,8 @@ extern int efipci_write ( struct pci_device *pci, unsigned long location,
  */
 static inline __always_inline int
 PCIAPI_INLINE ( efi, pci_num_bus ) ( void ) {
-	/* No way to work this out via EFI */
-	return 0x100;
+	/* EFI does not want us to scan the PCI bus ourselves */
+	return 0;
 }
 
 /**
@@ -145,4 +145,4 @@ PCIAPI_INLINE ( efi, pci_write_config_dword ) ( struct pci_device *pci,
 			      value );
 }
 
-#endif /* _IPXE_EFI_PCI_H */
+#endif /* _IPXE_EFI_PCI_API_H */
diff --git a/src/include/ipxe/pci_io.h b/src/include/ipxe/pci_io.h
index dab5b780..7368cf48 100644
--- a/src/include/ipxe/pci_io.h
+++ b/src/include/ipxe/pci_io.h
@@ -43,7 +43,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 	PROVIDE_SINGLE_API_INLINE ( PCIAPI_PREFIX_ ## _subsys, _api_func )
 
 /* Include all architecture-independent I/O API headers */
-#include <ipxe/efi/efi_pci.h>
+#include <ipxe/efi/efi_pci_api.h>
 
 /* Include all architecture-dependent I/O API headers */
 #include <bits/pci_io.h>