diff --git a/target/alpha/cpu.c b/target/alpha/cpu.c
index 5d75c941f7a..70f67e6fd4e 100644
--- a/target/alpha/cpu.c
+++ b/target/alpha/cpu.c
@@ -199,6 +199,8 @@ static void alpha_cpu_initfn(Object *obj)
* operand in Fa. That is float_2nan_prop_ba.
*/
set_float_2nan_prop_rule(float_2nan_prop_x87, &env->fp_status);
+ /* Default NaN: sign bit clear, msb frac bit set */
+ set_float_default_nan_pattern(0b01000000, &env->fp_status);
#if defined(CONFIG_USER_ONLY)
env->flags = ENV_FLAG_PS_USER | ENV_FLAG_FEN;
cpu_alpha_store_fpcr(env, (uint64_t)(FPCR_INVD | FPCR_DZED | FPCR_OVFD