diff --git a/Make.test-suite b/Make.test-suite
index 60e8567..ec012dc 100644
--- a/Make.test-suite
+++ b/Make.test-suite
@@ -1,6 +1,8 @@
 examples/boolean.v
 examples/divmod.v
 examples/zagier.v
+examples/test_ssreflect.v
+examples/test_algebra.v
 
 -I .
 -arg -w -arg -notation-overridden
diff --git a/examples/test_algebra.v b/examples/test_algebra.v
new file mode 100644
index 0000000..2d26d0d
--- /dev/null
+++ b/examples/test_algebra.v
@@ -0,0 +1,12 @@
+From Coq Require Import BinInt Zify.
+From mathcomp Require Import all_ssreflect all_algebra zify ssrZ.
+
+Set Implicit Arguments.
+Unset Strict Implicit.
+Unset Printing Implicit Defensive.
+
+Local Delimit Scope Z_scope with Z.
+
+Fact test_unit_int m :
+  m \is a GRing.unit = (Z_of_int m =? 1)%Z || (Z_of_int m =? - 1)%Z.
+Proof. zify_pre_hook; zify_op; reflexivity. Qed.
diff --git a/examples/test_ssreflect.v b/examples/test_ssreflect.v
index a9a3655..09deb5a 100644
--- a/examples/test_ssreflect.v
+++ b/examples/test_ssreflect.v
@@ -238,4 +238,92 @@ Proof. zify_op; reflexivity. Qed.
 Fact test_bottom_nat : Z.of_nat 0%O = 0%Z.
 Proof. zify_op; reflexivity. Qed.
 
-(* TODO: division / modulo *)
+(******************************************************************************)
+(* div (divn, modn, dvdn, gcdn, lcmn, and coprime)                            *)
+(******************************************************************************)
+
+Notation divZ := zify_ssreflect.SsreflectZifyInstances.divZ.
+Notation modZ := zify_ssreflect.SsreflectZifyInstances.modZ.
+
+Fact test_divn n m : Z.of_nat (divn n m) = divZ (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_modn n m : Z.of_nat (modn n m) = modZ (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dvdn n m : dvdn n m = (modZ (Z.of_nat m) (Z.of_nat n) =? 0)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_odd n : odd n = (modZ (Z.of_nat n) 2 =? 1)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_odd_trec n : NatTrec.odd n = (modZ (Z.of_nat n) 2 =? 1)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_half n : Z.of_nat (half n) = divZ (Z.of_nat n) 2.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_uphalf n : Z.of_nat (uphalf n) = divZ (Z.of_nat n + 1) 2.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_gcdn n m : Z.of_nat (gcdn n m) = Z.gcd (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_lcmn n m : Z.of_nat (lcmn n m) = Z.lcm (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_coprime n m : coprime n m = (Z.gcd (Z.of_nat n) (Z.of_nat m) =? 1)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+(******************************************************************************)
+(* natdvd in order.v                                                          *)
+(******************************************************************************)
+
+Fact test_le_natdvd (n m : natdvd) :
+  (n <= m)%O = (modZ (Z.of_nat m) (Z.of_nat n) =? 0)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_lt_natdvd (n m : natdvd) :
+  (n < m)%O =
+    ~~ (Z.of_nat m =? Z.of_nat n)%Z && (modZ (Z.of_nat m) (Z.of_nat n) =? 0)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dual_le_natdvd (n m : natdvd^d) :
+  (m <= n)%O = (modZ (Z.of_nat m) (Z.of_nat n) =? 0)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dual_lt_natdvd (n m : natdvd^d) :
+  (m < n)%O =
+    ~~ (Z.of_nat m =? Z.of_nat n)%Z && (modZ (Z.of_nat m) (Z.of_nat n) =? 0)%Z.
+Proof. zify_op; reflexivity. Qed.
+
+(* FIXME: ge, gt *)
+
+Fact test_meet_natdvd (n m : natdvd) :
+  Z.of_nat (n `&` m)%O = Z.gcd (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_join_natdvd (n m : natdvd) :
+  Z.of_nat (n `|` m)%O = Z.lcm (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dual_meet_natdvd (n m : natdvd^d) :
+  Z.of_nat (n `&` m)%O = Z.lcm (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dual_join_natdvd (n m : natdvd^d) :
+  Z.of_nat (n `|` m)%O = Z.gcd (Z.of_nat n) (Z.of_nat m).
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_bottom_natdvd : Z.of_nat (0%O : natdvd) = 1%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_top_natdvd : Z.of_nat (1%O : natdvd) = 0%Z.
+Proof. zify_op; reflexivity. Qed.
+
+(* FIXME: Notations 0^d and 1^d are broken. *)
+Fact test_dual_bottom_natdvd : Z.of_nat (0%O : natdvd^d) = 0%Z.
+Proof. zify_op; reflexivity. Qed.
+
+Fact test_dual_top_natdvd : Z.of_nat (1%O : natdvd^d) = 1%Z.
+Proof. zify_op; reflexivity. Qed.
diff --git a/theories/zify_ssreflect.v b/theories/zify_ssreflect.v
index 87185f6..822fb03 100644
--- a/theories/zify_ssreflect.v
+++ b/theories/zify_ssreflect.v
@@ -486,9 +486,15 @@ Instance Op_natdvd_bottom : CstOp (0%O : natdvd) :=
   { TCst := 1%Z; TCstInj := erefl }.
 Add Zify CstOp Op_natdvd_bottom.
 
+Instance Op_natdvd_bottom' : CstOp (1%O : natdvd^d) := Op_natdvd_bottom.
+Add Zify CstOp Op_natdvd_bottom'.
+
 Instance Op_natdvd_top : CstOp (1%O : natdvd) := Op_O.
 Add Zify CstOp Op_natdvd_top.
 
+Instance Op_natdvd_top' : CstOp (0%O : natdvd^d) := Op_O.
+Add Zify CstOp Op_natdvd_top'.
+
 Module Exports.
 (* Add Zify UnOp Op_bool_inj. *)
 (* Add Zify UnOp Op_nat_inj. *)
@@ -586,7 +592,9 @@ Add Zify BinOp Op_natdvd_meet'.
 Add Zify BinOp Op_natdvd_join.
 Add Zify BinOp Op_natdvd_join'.
 Add Zify CstOp Op_natdvd_bottom.
+Add Zify CstOp Op_natdvd_bottom'.
 Add Zify CstOp Op_natdvd_top.
+Add Zify CstOp Op_natdvd_top'.
 End Exports.
 
 End SsreflectZifyInstances.