diff --git a/libsharp/sharp.c b/libsharp/sharp.c
index 38fd3f2..b3aad26 100644
--- a/libsharp/sharp.c
+++ b/libsharp/sharp.c
@@ -176,7 +176,7 @@ void sharp_make_geom_info (int nrings, const int *nph, const ptrdiff_t *ofs,
     infos[m].theta = theta[m];
     infos[m].cth = cos(theta[m]);
     infos[m].sth = sin(theta[m]);
-    infos[m].weight = weight[m];
+    infos[m].weight = (weight != NULL) ? weight[m] : 1.;
     infos[m].phi0 = phi0[m];
     infos[m].ofs = ofs[m];
     infos[m].stride = stride[m];
diff --git a/libsharp/sharp_lowlevel.h b/libsharp/sharp_lowlevel.h
index 96e10dd..e7368f1 100644
--- a/libsharp/sharp_lowlevel.h
+++ b/libsharp/sharp_lowlevel.h
@@ -123,7 +123,9 @@ void sharp_destroy_alm_info (sharp_alm_info *info);
     \param stride the stride between consecutive pixels
     \param phi0 the azimuth (in radians) of the first pixel in each ring
     \param theta the colatitude (in radians) of each ring
-    \param weight the pixel weight to be used for the ring
+    \param weight the pixel weight to be used for the ring. Pass NULL to use
+      1.0 as weight for all rings. By default weights are used for alm2map
+      but not map2alm, but the execution flags can override this.
     \param geom_info will hold a pointer to the newly created data structure
  */
 void sharp_make_geom_info (int nrings, const int *nph, const ptrdiff_t *ofs,