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 91817ad5f9..6bca48fe9a 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
@@ -122,6 +122,8 @@ struct Hw::Tsc
 			"rdtsc;"
 			"lfence;"
 			: "=a"(low), "=d"(high)
+			:
+			: "memory"
 		);
 		return (Genode::uint64_t)(high) << 32 | low;
 	}