diff --git a/src/converters/convertScalar.test.ts b/src/converters/convertScalar.test.ts
index 15c72ae..fc2cc0e 100644
--- a/src/converters/convertScalar.test.ts
+++ b/src/converters/convertScalar.test.ts
@@ -92,19 +92,33 @@ describe('convertScalar', () => {
     ).toBe(SDL.ID);
   });
 
-  it('converts @unique to ID if no @id exists', () => {
+  it('converts solo @unique to ID if no @id exists', () => {
     expect(
       convertScalar(
         {type: PSL.String, isUnique: true, isId: false} as DMMF.Field,
-        {name: 'User', fields: [{isId: false}]} as DMMF.Model,
+        {
+          name: 'User',
+          fields: [
+            {type: PSL.String, isUnique: true, isId: false},
+            {type: PSL.Int, isUnique: false, isId: false},
+          ],
+        } as DMMF.Model,
       ),
     ).toBe(SDL.ID);
+  });
 
+  it('does nothing for multiple @unique even if no @id exists', () => {
     expect(
       convertScalar(
         {type: PSL.String, isUnique: true, isId: false} as DMMF.Field,
-        {name: 'User', fields: [{isId: true}]} as DMMF.Model,
+        {
+          name: 'User',
+          fields: [
+            {type: PSL.String, isUnique: true, isId: false} as DMMF.Field,
+            {type: PSL.Int, isUnique: true, isId: false} as DMMF.Field,
+          ],
+        } as DMMF.Model,
       ),
-    ).toBe(SDL.String);
+    ).toBe(PSL.String);
   });
 });
diff --git a/src/converters/rules/scalar.ts b/src/converters/rules/scalar.ts
index 0d7602f..90532bd 100644
--- a/src/converters/rules/scalar.ts
+++ b/src/converters/rules/scalar.ts
@@ -1,5 +1,6 @@
 import {PSL, Rule, SDL, Scalar} from '../types';
 import extractId from 'extractors/extractId';
+import extractUniques from 'extractors/extractUniques';
 
 const rules: Rule[] = [
   {
@@ -60,11 +61,12 @@ const rules: Rule[] = [
   },
   {
     matcher: (field, model) => {
-      const idField = extractId(model);
-
       const {isUnique} = field;
 
-      return !idField && isUnique;
+      const idField = extractId(model);
+      const uniqueFields = extractUniques(model);
+
+      return !idField && uniqueFields.length === 1 && isUnique;
     },
     transformer: () => SDL.ID,
   },
diff --git a/src/extractors/extractUniques.test.ts b/src/extractors/extractUniques.test.ts
new file mode 100644
index 0000000..37979c5
--- /dev/null
+++ b/src/extractors/extractUniques.test.ts
@@ -0,0 +1,20 @@
+import {DMMF} from '@prisma/generator-helper';
+
+import extractUniques from './extractUniques';
+
+describe('extractUniques', () => {
+  it('extracts all fields that is @unique', () => {
+    const model = {
+      fields: [
+        {name: '1', isUnique: true} as DMMF.Field,
+        {name: '2', isUnique: false} as DMMF.Field,
+        {name: '3', isUnique: true} as DMMF.Field,
+      ],
+    } as DMMF.Model;
+
+    expect(extractUniques(model)).toEqual([
+      {name: '1', isUnique: true} as DMMF.Field,
+      {name: '3', isUnique: true} as DMMF.Field,
+    ]);
+  });
+});
diff --git a/src/extractors/extractUniques.ts b/src/extractors/extractUniques.ts
new file mode 100644
index 0000000..cfedae4
--- /dev/null
+++ b/src/extractors/extractUniques.ts
@@ -0,0 +1,7 @@
+import {DMMF} from '@prisma/generator-helper';
+
+const extractUniques = (model: DMMF.Model): DMMF.Field[] => {
+  return model.fields.filter(({isUnique}) => isUnique);
+};
+
+export default extractUniques;