Index: kernel/arch/amd64/include/cpu.h
===================================================================
--- kernel/arch/amd64/include/cpu.h	(revision 0cd21bfad0d0069f0e62f66d7dcacb27d6a92623)
+++ kernel/arch/amd64/include/cpu.h	(revision 80c941658b6963ac942c8ada940935259b73c370)
@@ -45,4 +45,5 @@
 #define RFLAGS_DF	(1 << 10)
 #define RFLAGS_OF	(1 << 11)
+#define RFLAGS_NT	(1 << 14)
 #define RFLAGS_RF	(1 << 16)
 
Index: kernel/arch/amd64/src/syscall.c
===================================================================
--- kernel/arch/amd64/src/syscall.c	(revision 0cd21bfad0d0069f0e62f66d7dcacb27d6a92623)
+++ kernel/arch/amd64/src/syscall.c	(revision 80c941658b6963ac942c8ada940935259b73c370)
@@ -66,6 +66,7 @@
 	 * - clear DF so that the string instructions operate in
 	 *   the right direction
+	 * - clear NT to prevent a #GP should the flag proliferate to an IRET
 	 */
-	write_msr(AMD_MSR_SFMASK, RFLAGS_IF | RFLAGS_DF);
+	write_msr(AMD_MSR_SFMASK, RFLAGS_IF | RFLAGS_DF | RFLAGS_NT);
 }