diff --git a/sys/amd64/amd64/fpu.c b/sys/amd64/amd64/fpu.c
index 562951e2d7e..91ceab232dd 100644
--- a/sys/amd64/amd64/fpu.c
+++ b/sys/amd64/amd64/fpu.c
@@ -318,13 +318,15 @@ fpuinitstate(void *arg __unused)
 		cpu_mxcsr_mask = 0xFFBF;
 
 	/*
-	 * The fninit instruction does not modify XMM registers.  The
-	 * fpusave call dumped the garbage contained in the registers
-	 * after reset to the initial state saved.  Clear XMM
-	 * registers file image to make the startup program state and
-	 * signal handler XMM register content predictable.
+	 * The fninit instruction does not modify XMM registers or x87
+	 * registers (MM/ST).  The fpusave call dumped the garbage
+	 * contained in the registers after reset to the initial state
+	 * saved.  Clear XMM and x87 registers file image to make the
+	 * startup program state and signal handler XMM/x87 register
+	 * content predictable.
 	 */
-	bzero(&fpu_initialstate->sv_xmm[0], sizeof(struct xmmacc));
+	bzero(fpu_initialstate->sv_fp, sizeof(fpu_initialstate->sv_fp));
+	bzero(fpu_initialstate->sv_xmm, sizeof(fpu_initialstate->sv_xmm));
 
 	/*
 	 * Create a table describing the layout of the CPU Extended