diff --git a/src/hope_dedup_engine/apps/api/migrations/0001_initial.py b/src/hope_dedup_engine/apps/api/migrations/0001_initial.py
index d4d09d12..9a1a30a3 100644
--- a/src/hope_dedup_engine/apps/api/migrations/0001_initial.py
+++ b/src/hope_dedup_engine/apps/api/migrations/0001_initial.py
@@ -1,4 +1,4 @@
-# Generated by Django 5.0.6 on 2024-05-22 13:24
+# Generated by Django 5.0.6 on 2024-05-24 11:45
 
 import django.db.models.deletion
 import uuid
@@ -21,7 +21,7 @@ class Migration(migrations.Migration):
             fields=[
                 ("id", models.UUIDField(default=uuid.uuid4, primary_key=True, serialize=False)),
                 ("name", models.CharField(max_length=100)),
-                ("reference_pk", models.IntegerField()),
+                ("reference_pk", models.CharField(max_length=100)),
                 (
                     "state",
                     models.IntegerField(
@@ -62,9 +62,9 @@ class Migration(migrations.Migration):
             name="Duplicate",
             fields=[
                 ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
-                ("first_reference_pk", models.IntegerField()),
+                ("first_reference_pk", models.CharField(max_length=100)),
                 ("first_filename", models.CharField(max_length=255)),
-                ("second_reference_pk", models.IntegerField()),
+                ("second_reference_pk", models.CharField(max_length=100)),
                 ("second_filename", models.CharField(max_length=255)),
                 ("score", models.FloatField()),
                 (
@@ -97,7 +97,7 @@ class Migration(migrations.Migration):
             name="Image",
             fields=[
                 ("id", models.UUIDField(default=uuid.uuid4, primary_key=True, serialize=False)),
-                ("reference_pk", models.IntegerField()),
+                ("reference_pk", models.CharField(max_length=100)),
                 ("filename", models.CharField(max_length=255)),
                 ("created_at", models.DateTimeField(auto_now_add=True)),
                 (
diff --git a/src/hope_dedup_engine/apps/api/models/deduplication.py b/src/hope_dedup_engine/apps/api/models/deduplication.py
index 7a54d838..817d6a80 100644
--- a/src/hope_dedup_engine/apps/api/models/deduplication.py
+++ b/src/hope_dedup_engine/apps/api/models/deduplication.py
@@ -5,6 +5,8 @@
 
 from hope_dedup_engine.apps.security.models import ExternalSystem
 
+REFERENCE_PK_LENGTH = 100
+
 
 class DeduplicationSet(models.Model):
     class State(models.IntegerChoices):
@@ -15,7 +17,7 @@ class State(models.IntegerChoices):
 
     id = models.UUIDField(primary_key=True, default=uuid4)
     name = models.CharField(max_length=100)
-    reference_pk = models.IntegerField()
+    reference_pk = models.CharField(max_length=REFERENCE_PK_LENGTH)
     state = models.IntegerField(
         choices=State.choices,
         default=State.CLEAN,
@@ -36,7 +38,7 @@ class State(models.IntegerChoices):
 class Image(models.Model):
     id = models.UUIDField(primary_key=True, default=uuid4)
     deduplication_set = models.ForeignKey(DeduplicationSet, on_delete=models.CASCADE)
-    reference_pk = models.IntegerField()
+    reference_pk = models.CharField(max_length=REFERENCE_PK_LENGTH)
     filename = models.CharField(max_length=255)
     created_by = models.ForeignKey(
         settings.AUTH_USER_MODEL, on_delete=models.CASCADE, null=True, blank=True, related_name="+"
@@ -46,8 +48,8 @@ class Image(models.Model):
 
 class Duplicate(models.Model):
     deduplication_set = models.ForeignKey(DeduplicationSet, on_delete=models.CASCADE)
-    first_reference_pk = models.IntegerField()
+    first_reference_pk = models.CharField(max_length=REFERENCE_PK_LENGTH)
     first_filename = models.CharField(max_length=255)
-    second_reference_pk = models.IntegerField()
+    second_reference_pk = models.CharField(max_length=REFERENCE_PK_LENGTH)
     second_filename = models.CharField(max_length=255)
     score = models.FloatField()
diff --git a/tests/api/test_deduplication_set_create.py b/tests/api/test_deduplication_set_create.py
index 1dd2d71e..62973d03 100644
--- a/tests/api/test_deduplication_set_create.py
+++ b/tests/api/test_deduplication_set_create.py
@@ -47,9 +47,7 @@ def test_missing_fields_handling(api_client: APIClient, omit: str | tuple[str, .
     (
         ("name", ""),
         ("name", None),
-        ("reference_pk", "foo"),
         ("reference_pk", None),
-        ("reference_pk", 3.14),
     ),
 )
 def test_invalid_values_handling(api_client: APIClient, field: str, value: Any) -> None:
diff --git a/tests/extras/testutils/factories/api.py b/tests/extras/testutils/factories/api.py
index 8d137d9e..66bef975 100644
--- a/tests/extras/testutils/factories/api.py
+++ b/tests/extras/testutils/factories/api.py
@@ -13,7 +13,7 @@ class Meta:
 
 class DeduplicationSetFactory(DjangoModelFactory):
     name = fuzzy.FuzzyText()
-    reference_pk = fuzzy.FuzzyInteger(low=1)
+    reference_pk = fuzzy.FuzzyText()
     external_system = SubFactory(ExternalSystemFactory)
     state = DeduplicationSet.State.CLEAN
 
@@ -24,7 +24,7 @@ class Meta:
 class ImageFactory(DjangoModelFactory):
     deduplication_set = SubFactory(DeduplicationSetFactory)
     filename = fuzzy.FuzzyText()
-    reference_pk = fuzzy.FuzzyInteger(low=1)
+    reference_pk = fuzzy.FuzzyText()
 
     class Meta:
         model = Image
@@ -33,9 +33,9 @@ class Meta:
 class DuplicateFactory(DjangoModelFactory):
     deduplication_set = SubFactory(DeduplicationSetFactory)
     first_filename = fuzzy.FuzzyText()
-    first_reference_pk = fuzzy.FuzzyInteger(low=1)
+    first_reference_pk = fuzzy.FuzzyText()
     second_filename = fuzzy.FuzzyText()
-    second_reference_pk = fuzzy.FuzzyInteger(low=1)
+    second_reference_pk = fuzzy.FuzzyText()
     score = fuzzy.FuzzyFloat(low=0, high=1)
 
     class Meta: