diff --git a/kernel/zarch/cscal.c b/kernel/zarch/cscal.c
index a07429caf..0b265d783 100644
--- a/kernel/zarch/cscal.c
+++ b/kernel/zarch/cscal.c
@@ -382,7 +382,7 @@ int CNAME(BLASLONG n, BLASLONG dummy0, BLASLONG dummy1, FLOAT da_r, FLOAT da_i,
           x[i + 1] = da_i * x[i];
 	else
 	  x[i + 1] = NAN;
-	if (!isnan(x[i]))
+	if (x[i] == x[i])
           x[i] = temp0;
         i += 2;
         j++;