Index: sys/arm64/arm64/machdep.c
===================================================================
--- sys/arm64/arm64/machdep.c
+++ sys/arm64/arm64/machdep.c
@@ -539,7 +539,7 @@
 
 	spsr = uc.uc_mcontext.mc_gpregs.gp_spsr;
 	if ((spsr & PSR_M_MASK) != PSR_M_EL0t ||
-	    (spsr & (PSR_F | PSR_I | PSR_A | PSR_D)) != 0)
+	    (spsr & (PSR_AARCH32 | PSR_F | PSR_I | PSR_A | PSR_D)) != 0)
 		return (EINVAL); 
 
 	set_mcontext(td, &uc.uc_mcontext);
Index: sys/arm64/include/armreg.h
===================================================================
--- sys/arm64/include/armreg.h
+++ sys/arm64/include/armreg.h
@@ -548,7 +548,6 @@
 /* SPSR_EL1 */
 /*
  * When the exception is taken in AArch64:
- * M[4]   is 0 for AArch64 mode
  * M[3:2] is the exception level
  * M[1]   is unused
  * M[0]   is the SP select:
@@ -560,8 +559,9 @@
 #define	PSR_M_EL1h	0x00000005
 #define	PSR_M_EL2t	0x00000008
 #define	PSR_M_EL2h	0x00000009
-#define	PSR_M_MASK	0x0000001f
+#define	PSR_M_MASK	0x0000000f
 
+#define	PSR_AARCH32	0x00000010
 #define	PSR_F		0x00000040
 #define	PSR_I		0x00000080
 #define	PSR_A		0x00000100