diff --git a/src/add-ons/kernel/busses/pci/ecam/ECAMPCIController.cpp b/src/add-ons/kernel/busses/pci/ecam/ECAMPCIController.cpp
index b283cddc61..686e8e8c0f 100644
--- a/src/add-ons/kernel/busses/pci/ecam/ECAMPCIController.cpp
+++ b/src/add-ons/kernel/busses/pci/ecam/ECAMPCIController.cpp
@@ -166,10 +166,7 @@ ECAMPCIController::ConfigAddress(uint8 bus, uint8 device, uint8 function, uint16
 		.device = device,
 		.bus = bus
 	};
-	PciAddressEcam addressEnd = address;
-	addressEnd.offset = /*~(uint32)0*/ 4095;
-
-	if (addressEnd.val >= fRegsLen)
+	if ((address.val + 4) > fRegsLen)
 		return 0;
 
 	return (addr_t)fRegs + address.val;
diff --git a/src/add-ons/kernel/busses/pci/ecam/ECAMPCIControllerACPI.cpp b/src/add-ons/kernel/busses/pci/ecam/ECAMPCIControllerACPI.cpp
index a9bb59a817..c3aa3f2e3d 100644
--- a/src/add-ons/kernel/busses/pci/ecam/ECAMPCIControllerACPI.cpp
+++ b/src/add-ons/kernel/busses/pci/ecam/ECAMPCIControllerACPI.cpp
@@ -57,8 +57,9 @@ ECAMPCIControllerACPI::ReadResourceInfo()
 		uint8 startBusNumber = alloc->start_bus_number;
 		uint8 endBusNumber = alloc->end_bus_number;
 
+		fRegsLen = (endBusNumber - startBusNumber + 1) << 20;
 		fRegsArea.SetTo(map_physical_memory("PCI Config MMIO",
-			alloc->address, (endBusNumber - startBusNumber + 1) << 20, B_ANY_KERNEL_ADDRESS,
+			alloc->address, fRegsLen, B_ANY_KERNEL_ADDRESS,
 			B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA, (void **)&fRegs));
 		CHECK_RET(fRegsArea.Get());