diff --git a/caml_z_tommath.c b/caml_z_tommath.c
index fdbbfbb..412cbeb 100644
--- a/caml_z_tommath.c
+++ b/caml_z_tommath.c
@@ -1357,9 +1357,33 @@ CAMLprim value ml_z_sqrt(value arg)
   CAMLreturn(r);
 }
 
-CAMLprim value ml_z_sqrt_rem(UNUSED_PARAM value arg)
+CAMLprim value ml_z_sqrt_rem(value arg)
 {
-  caml_failwith("Z.sqrt_rem: not implemented in LibTomMath backend");
+  CAMLparam1(arg);
+  CAMLlocal3(r1,r2,r);
+  Z_DECL(arg);
+  Z_ARG(arg);
+  if (mp_isneg(mp_arg)) {
+    Z_END_ARG(arg);
+    caml_invalid_argument("Z.sqrt_rem: square root of a negative number");
+  }
+  r1 = ml_z_alloc();
+  r2 = ml_z_alloc();
+  Z_REFRESH(arg);
+  if (mp_sqrt(mp_arg, Z_MP(r1)) != MP_OKAY ||
+      mp_mul(Z_MP(r1),Z_MP(r1),Z_MP(r2)) != MP_OKAY ||
+      mp_sub(mp_arg,Z_MP(r2),Z_MP(r2)) != MP_OKAY) {
+    caml_failwith("Z.sqrt_rem: internal error");
+    Z_END_ARG(arg);
+  }
+  r1 = ml_z_reduce(r1);
+  r2 = ml_z_reduce(r2);
+  r = caml_alloc_small(2, 0);
+  Field(r,0) = r1;
+  Field(r,1) = r2;
+  Z_END_ARG(arg);
+  CAMLreturn(r);
+  //caml_failwith("Z.sqrt_rem: not implemented in LibTomMath backend");
 }
 
 CAMLprim value ml_z_gcd(value arg1, value arg2)
diff --git a/tests/zq.output-LibTomMath-64-60 b/tests/zq.output-LibTomMath-64-60
index 43b09b8..69a3708 100644
--- a/tests/zq.output-LibTomMath-64-60
+++ b/tests/zq.output-LibTomMath-64-60
@@ -867,7 +867,16 @@ sqrt 2^120
  = 1152921504606846976
 sqrt 2^121
  = 1630477228166597776
-Failure: Z.sqrt_rem: not implemented in LibTomMath backend
+sqrt_rem 0
+ = 0, 0
+sqrt_rem 1
+ = 1, 0
+sqrt_rem 2
+ = 1, 1
+sqrt_rem 2^120
+ = 1152921504606846976, 0
+sqrt_rem 2^121
+ = 1630477228166597776, 1772969445592542976
 popcount 0
  = 0
 popcount 1