Index: kernel/arch/amd64/src/syscall.c
===================================================================
--- kernel/arch/amd64/src/syscall.c	(revision d2f75eb31efa7109d60f52eb578fddc21c8d1e2d)
+++ kernel/arch/amd64/src/syscall.c	(revision b277bef17cacdcab109f936194b7f7b6e0d05213)
@@ -66,6 +66,8 @@
 	 *   the right direction
 	 * - clear NT to prevent a #GP should the flag proliferate to an IRET
+	 * - clear TF to prevent an immediate #DB if TF is set
 	 */
-	write_msr(AMD_MSR_SFMASK, RFLAGS_IF | RFLAGS_DF | RFLAGS_NT);
+	write_msr(AMD_MSR_SFMASK,
+	    RFLAGS_IF | RFLAGS_DF | RFLAGS_NT | RFLAGS_TF);
 }