diff --git a/src/c/number.d b/src/c/number.d
index dac770193..4497e5980 100644
--- a/src/c/number.d
+++ b/src/c/number.d
@@ -922,5 +922,6 @@ cl_object
 si_nan() {
   cl_object x = ecl_alloc_object(t_doublefloat);
   ecl_double_float(x) = NAN;
+  return NAN;
 }
 #endif /* ECL_IEEE_FP */