diff --git a/squeaknode/db/alembic/versions/cd3f18ee33c8_add_unique_constraint_on_payment_hash_.py b/squeaknode/db/alembic/versions/cd3f18ee33c8_add_unique_constraint_on_payment_hash_.py
new file mode 100644
index 00000000..f5eed1c8
--- /dev/null
+++ b/squeaknode/db/alembic/versions/cd3f18ee33c8_add_unique_constraint_on_payment_hash_.py
@@ -0,0 +1,33 @@
+"""Add unique constraint on payment hash of received offer
+
+Revision ID: cd3f18ee33c8
+Revises: df59995f322c
+Create Date: 2021-01-27 17:40:06.995928
+
+"""
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = 'cd3f18ee33c8'
+down_revision = 'df59995f322c'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('received_offer', schema=None) as batch_op:
+        batch_op.create_unique_constraint(
+            'uq_received_offer_payment_hash', ['payment_hash'])
+
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('received_offer', schema=None) as batch_op:
+        batch_op.drop_constraint(
+            'uq_received_offer_payment_hash', type_='unique')
+
+    # ### end Alembic commands ###
diff --git a/squeaknode/db/models.py b/squeaknode/db/models.py
index 33f2886f..2ec27d47 100644
--- a/squeaknode/db/models.py
+++ b/squeaknode/db/models.py
@@ -87,7 +87,7 @@ class Models:
             Column("created", TZDateTime,
                    server_default=func.now(), nullable=False),
             Column("squeak_hash", String(64), nullable=False),
-            Column("payment_hash", String(64), nullable=False),
+            Column("payment_hash", String(64), unique=True, nullable=False),
             Column("nonce", String(64), nullable=False),
             Column("payment_point", String(66), nullable=False),
             Column("invoice_timestamp", Integer, nullable=False),