diff --git a/acb_dirichlet/l.c b/acb_dirichlet/l.c
index 8dedba26..d010b75f 100644
--- a/acb_dirichlet/l.c
+++ b/acb_dirichlet/l.c
@@ -51,7 +51,7 @@ acb_dirichlet_l(acb_t res, const acb_t s,
     {
         acb_indeterminate(res);
     }
-    else if (G->q == 1)
+    else if (G == NULL || G->q == 1)
     {
         acb_dirichlet_zeta(res, s, prec);
     }
diff --git a/acb_dirichlet/l_jet.c b/acb_dirichlet/l_jet.c
index 6397851c..80140617 100644
--- a/acb_dirichlet/l_jet.c
+++ b/acb_dirichlet/l_jet.c
@@ -28,7 +28,7 @@ acb_dirichlet_l_jet(acb_ptr res, const acb_t s,
         return;
 
     /* todo: reflection formula */
-    if (G->q == 1)
+    if (G == NULL || G->q == 1)
     {
         acb_init(a);
         acb_one(a);
diff --git a/doc/source/acb_dirichlet.rst b/doc/source/acb_dirichlet.rst
index ad3a1953..b8682dcb 100644
--- a/doc/source/acb_dirichlet.rst
+++ b/doc/source/acb_dirichlet.rst
@@ -429,6 +429,9 @@ L-functions
 Hardy Z-functions
 -------------------------------------------------------------------------------
 
+For convenience, setting both *G* and *chi* to *NULL* in the following
+methods selects the Riemann zeta function.
+
 .. function:: void acb_dirichlet_hardy_theta(acb_ptr res, const acb_t t, const dirichlet_group_t G, const dirichlet_char_t chi, slong len, slong prec)
 
     Computes the phase function used to construct the Z-function.