diff -up src/sage/libs/eclib/mwrank.pyx.orig src/sage/libs/eclib/mwrank.pyx
--- src/sage/libs/eclib/mwrank.pyx.orig	2021-05-09 16:00:11.000000000 -0600
+++ src/sage/libs/eclib/mwrank.pyx	2021-07-07 09:31:20.972526814 -0600
@@ -55,7 +55,7 @@ cdef extern from "wrap.cpp":
     char* mw_getbasis(mw* m)
     double mw_regulator(mw* m)
     int mw_rank(mw* m)
-    int mw_saturate(mw* m, bigint* index, char** unsat,
+    int mw_saturate(mw* m, long* index, char** unsat,
                     long sat_bd, int odd_primes_only)
     void mw_search(mw* m, char* h_lim, int moduli_option, int verb)
 
@@ -894,12 +894,12 @@ cdef class _mw:
 
 
         """
-        cdef _bigint index
+        cdef long index
         cdef char* s
         cdef int ok
         sig_on()
-        index = _bigint()
-        ok = mw_saturate(self.x, index.x, &s, sat_bd, odd_primes_only)
+        index = 0
+        ok = mw_saturate(self.x, &index, &s, sat_bd, odd_primes_only)
         unsat = string_sigoff(s)
         return ok, index, unsat
 
diff -up src/sage/libs/eclib/wrap.cpp.orig src/sage/libs/eclib/wrap.cpp
--- src/sage/libs/eclib/wrap.cpp.orig	2021-05-09 16:00:11.000000000 -0600
+++ src/sage/libs/eclib/wrap.cpp	2021-07-06 17:38:03.377018615 -0600
@@ -178,7 +178,7 @@ int mw_rank(struct mw* m)
 }
 
 /* Returns index and unsat long array, which user must deallocate */
-int mw_saturate(struct mw* m, bigint* index, char** unsat,
+int mw_saturate(struct mw* m, long* index, char** unsat,
                        long sat_bd, int odd_primes_only)
 {
   vector<long> v;