diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index 525db61741..5fcdbc87fd 100644
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -106,7 +106,7 @@ static FloatPartsN *partsN(pick_nan_muladd)(FloatPartsN *a, FloatPartsN *b,
         }
         ret = c;
     } else {
-        FloatPartsN *val[3] = { a, b, c };
+        FloatPartsN *val[R_3NAN_1ST_MASK + 1] = { a, b, c };
         Float3NaNPropRule rule = s->float_3nan_prop_rule;
 
         assert(rule != float_3nan_prop_none);