X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/5b295848664fa50612fb2df8aba58f29f9f74d63..HEAD:/math/mp-modsqrt.c

diff --git a/math/mp-modsqrt.c b/math/mp-modsqrt.c
index c5aed1fa..f7a74148 100644
--- a/math/mp-modsqrt.c
+++ b/math/mp-modsqrt.c
@@ -63,12 +63,18 @@ mp *mp_modsqrt(mp *d, mp *a, mp *p)
   mp *r, *A, *aa;
   mp *t;
   grand *gr;
+  int j;
 
   /* --- Cope if %$a \not\in Q_p$% --- */
 
-  if (mp_jacobi(a, p) != 1) {
+  j = mp_jacobi(a, p);
+  if (j == -1) {
     mp_drop(d);
     return (0);
+  } else if (j == 0) {
+    if (d != a) mp_drop(d);
+    d = MP_COPY(a);
+    return (d);
   }
 
   /* --- Choose some quadratic non-residue --- */