diff --git a/repos/base-hw/src/include/hw/spec/x86_64/x86_64.h b/repos/base-hw/src/include/hw/spec/x86_64/x86_64.h
index cc8a6b5ea79..9c003a5612f 100644
--- a/repos/base-hw/src/include/hw/spec/x86_64/x86_64.h
+++ b/repos/base-hw/src/include/hw/spec/x86_64/x86_64.h
@@ -121,6 +121,8 @@ struct Hw::Tsc
 			"rdtsc;"
 			"lfence;"
 			: "=a"(low), "=d"(high)
+			:
+			: "memory"
 		);
 		return (Genode::uint64_t)(high) << 32 | low;
 	}