diff --git a/repos/os/include/pci/config.h b/repos/os/include/pci/config.h
index 6e2580257b..d7751bd24e 100644
--- a/repos/os/include/pci/config.h
+++ b/repos/os/include/pci/config.h
@@ -142,10 +142,17 @@ struct Pci::Config : Genode::Mmio
 		bool prefetchable() {
 			return Bar_32bit::Memory_prefetchable::get(_conf()); }
 
-		Genode::size_t size()
+		Genode::uint64_t size()
 		{
-			return 1 + (memory() ? ~Bar_32bit::Memory_base::masked(_conf())
-			                     : ~Bar_32bit::Io_base::masked(_conf()));
+			if (memory()) {
+				Genode::uint64_t size = 1 + ~Bar_32bit::Memory_base::masked(_conf());
+				if (bit64())
+					size += ((Genode::uint64_t)~_get_and_set<Upper_bits>(read<Upper_bits>()))<<32;
+
+				return size;
+			}
+			else
+				return 1 + ~Bar_32bit::Io_base::masked(_conf());
 		}
 
 		Genode::uint64_t addr()
diff --git a/repos/os/src/app/pci_decode/main.cc b/repos/os/src/app/pci_decode/main.cc
index 653e49e189..c77be1054e 100644
--- a/repos/os/src/app/pci_decode/main.cc
+++ b/repos/os/src/app/pci_decode/main.cc
@@ -139,7 +139,7 @@ bus_t Main::parse_pci_function(Bdf             bdf,
 			}
 		});
 
-		cfg.for_each_bar([&] (uint64_t addr, size_t size,
+		cfg.for_each_bar([&] (uint64_t addr, uint64_t size,
 		                      unsigned bar, bool pf)
 		{
 			gen.node("io_mem", [&]
@@ -149,7 +149,7 @@ bus_t Main::parse_pci_function(Bdf             bdf,
 				gen.attribute("size",    string(size));
 				if (pf) gen.attribute("prefetchable", true);
 			});
-		}, [&] (uint64_t addr, size_t size, unsigned bar) {
+		}, [&] (uint64_t addr, uint64_t size, unsigned bar) {
 			gen.node("io_port_range", [&]
 			{
 				gen.attribute("pci_bar", bar);