diff --git a/packages/sdk/src/ts-schema-generator.ts b/packages/sdk/src/ts-schema-generator.ts
index 3a7e33bf..7a62e757 100644
--- a/packages/sdk/src/ts-schema-generator.ts
+++ b/packages/sdk/src/ts-schema-generator.ts
@@ -1074,7 +1074,7 @@ export class TsSchemaGenerator {
             : typeof arg === 'string'
               ? ts.factory.createStringLiteral(arg)
               : typeof arg === 'number'
-                ? ts.factory.createNumericLiteral(arg)
+                ? this.createNumberLiteral(arg)
                 : arg === true
                   ? ts.factory.createTrue()
                   : arg === false
@@ -1082,6 +1082,12 @@ export class TsSchemaGenerator {
                     : undefined;
     }
 
+    private createNumberLiteral(arg: number) {
+        return arg < 0
+            ? ts.factory.createPrefixUnaryExpression(ts.SyntaxKind.MinusToken, ts.factory.createNumericLiteral(-arg))
+            : ts.factory.createNumericLiteral(arg);
+    }
+
     private createProceduresObject(procedures: Procedure[]) {
         return ts.factory.createObjectLiteralExpression(
             procedures.map((proc) => ts.factory.createPropertyAssignment(proc.name, this.createProcedureObject(proc))),
diff --git a/tests/regression/test/issue-393.test.ts b/tests/regression/test/issue-393.test.ts
new file mode 100644
index 00000000..89d8c0b9
--- /dev/null
+++ b/tests/regression/test/issue-393.test.ts
@@ -0,0 +1,15 @@
+import { createTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('Regression for issue #393', () => {
+    it('verifies issue 393', async () => {
+        const db = await createTestClient(
+            `
+model users {
+  id String @id() @default(cuid())
+  tz Int @default(-6) @db.SmallInt()
+}`,
+        );
+        await expect(db.users.create({ data: {} })).resolves.toMatchObject({ tz: -6 });
+    });
+});