diff --git a/lib/pleroma/password.ex b/lib/pleroma/password.ex
index 2ce07bd9b..f8cba61a3 100644
--- a/lib/pleroma/password.ex
+++ b/lib/pleroma/password.ex
@@ -33,6 +33,7 @@ defmodule Pleroma.Password do
     false
   end
 
+  @spec maybe_update_password(User.t(), String.t()) :: {:ok, User.t()} | {:error, Ecto.Changeset.t()}
   def maybe_update_password(%User{password_hash: "$2" <> _} = user, password) do
     do_update_password(user, password)
   end
diff --git a/test/pleroma/password_test.exs b/test/pleroma/password_test.exs
new file mode 100644
index 000000000..951fc810a
--- /dev/null
+++ b/test/pleroma/password_test.exs
@@ -0,0 +1,65 @@
+defmodule Pleroma.PasswordTest do
+  use Pleroma.DataCase, async: true
+  import Pleroma.Factory
+  import ExUnit.CaptureLog
+
+  alias Pleroma.Password
+
+  describe "hash_pwd_salt/1" do
+    test "returns a hash" do
+      assert "$argon2id" <> _ = Password.hash_pwd_salt("test")
+    end
+  end
+
+  describe "maybe_update_password/2" do
+    test "with a bcrypt hash, it updates to an argon2 hash" do
+      user = insert(:user, password_hash: Bcrypt.hash_pwd_salt("123"))
+      assert "$2" <> _ = user.password_hash
+
+      {:ok, user} = Password.maybe_update_password(user, "123")
+      assert "$argon2" <> _ = user.password_hash
+    end
+
+    test "with a pbkdf2 hash, it updates to an argon2 hash" do
+      user = insert(:user, password_hash: Pleroma.Password.Pbkdf2.hash_pwd_salt("123"))
+      assert "$pbkdf2" <> _ = user.password_hash
+
+      {:ok, user} = Password.maybe_update_password(user, "123")
+      assert "$argon2" <> _ = user.password_hash
+    end
+  end
+
+  describe "checkpw/2" do
+    test "check pbkdf2 hash" do
+      hash =
+        "$pbkdf2-sha512$160000$loXqbp8GYls43F0i6lEfIw$AY.Ep.2pGe57j2hAPY635sI/6w7l9Q9u9Bp02PkPmF3OrClDtJAI8bCiivPr53OKMF7ph6iHhN68Rom5nEfC2A"
+
+      assert Password.checkpw("test-password", hash)
+      refute Password.checkpw("test-password1", hash)
+    end
+
+    test "check bcrypt hash" do
+      hash = "$2a$10$uyhC/R/zoE1ndwwCtMusK.TLVzkQ/Ugsbqp3uXI.CTTz0gBw.24jS"
+
+      assert Password.checkpw("password", hash)
+      refute Password.checkpw("password1", hash)
+    end
+
+    test "check argon2 hash" do
+      hash =
+        "$argon2id$v=19$m=65536,t=8,p=2$zEMMsTuK5KkL5AFWbX7jyQ$VyaQD7PF6e9btz0oH1YiAkWwIGZ7WNDZP8l+a/O171g"
+
+      assert Password.checkpw("password", hash)
+      refute Password.checkpw("password1", hash)
+    end
+
+    test "it returns false when hash invalid" do
+      hash =
+        "psBWV8gxkGOZWBz$PmfCycChoxeJ3GgGzwvhlgacb9mUoZ.KUXNCssekER4SJ7bOK53uXrHNb2e4i8yPFgSKyzaW9CcmrDXWIEMtD1"
+
+      assert capture_log(fn ->
+               refute Password.checkpw("password", hash)
+             end) =~ "[error] Password hash not recognized"
+    end
+  end
+end