diff --git a/quint/src/IRprinting.ts b/quint/src/IRprinting.ts
index d73379dbb..d63d6e6a0 100644
--- a/quint/src/IRprinting.ts
+++ b/quint/src/IRprinting.ts
@@ -195,9 +195,9 @@ export function sumToString(s: QuintSumType): string {
   return s.fields.fields
     .map((f: RowField) => {
       if (isTheUnit(f.fieldType)) {
-        ;`| ${f.fieldName}`
+        return `| ${f.fieldName}`
       } else {
-        ;`| ${f.fieldName}(${f.fieldType})`
+        return `| ${f.fieldName}(${typeToString(f.fieldType)})`
       }
     })
     .join('\n')
diff --git a/quint/test/IRprinting.test.ts b/quint/test/IRprinting.test.ts
index cf398cfd4..4013ad7e9 100644
--- a/quint/test/IRprinting.test.ts
+++ b/quint/test/IRprinting.test.ts
@@ -3,6 +3,7 @@ import { assert } from 'chai'
 import { buildDef, buildExpression, buildModuleWithDefs, buildType } from './builders/ir'
 import { definitionToString, expressionToString, moduleToString, typeToString } from '../src/IRprinting'
 import { toScheme } from '../src/types/base'
+import { QuintSumType, unitValue } from '../src'
 
 describe('moduleToString', () => {
   const quintModule = buildModuleWithDefs(['var S: Set[int]', 'val f = S.filter(x => x + 1)'])
@@ -219,6 +220,22 @@ describe('typeToString', () => {
     assert.deepEqual(typeToString(type), expectedType)
   })
 
+  it('pretty prints sum types', () => {
+    const type: QuintSumType = {
+      kind: 'sum',
+      fields: {
+        kind: 'row',
+        fields: [
+          { fieldName: 'A', fieldType: { kind: 'int', id: 0n } },
+          { fieldName: 'B', fieldType: unitValue(0n) },
+        ],
+        other: { kind: 'empty' },
+      },
+    }
+    const expectedType = '| A(int)\n| B'
+    assert.deepEqual(typeToString(type), expectedType)
+  })
+
   it('pretty prints union types', () => {
     const type = buildType('| { tag: "A", a: int } | { tag: "B", b: str }')
     const expectedType = '| { tag: "A", a: int }\n| { tag: "B", b: str }'