diff --git a/packages/@mantine/form/src/validators/has-length/has-length.ts b/packages/@mantine/form/src/validators/has-length/has-length.ts
index db626e43e28..44ecbd92896 100644
--- a/packages/@mantine/form/src/validators/has-length/has-length.ts
+++ b/packages/@mantine/form/src/validators/has-length/has-length.ts
@@ -27,7 +27,7 @@ function isLengthValid(payload: HasLengthPayload, value: any) {
 export function hasLength(payload: HasLengthPayload, error?: React.ReactNode) {
   const _error = error || true;
 
-  return (value: unknown) => {
+  return (value: unknown): React.ReactNode => {
     if (typeof value === 'string') {
       return isLengthValid(payload, value.trim()) ? null : _error;
     }
diff --git a/packages/@mantine/form/src/validators/is-in-range/is-in-range.ts b/packages/@mantine/form/src/validators/is-in-range/is-in-range.ts
index a831add08db..5a9206af16a 100644
--- a/packages/@mantine/form/src/validators/is-in-range/is-in-range.ts
+++ b/packages/@mantine/form/src/validators/is-in-range/is-in-range.ts
@@ -6,7 +6,7 @@ interface IsInRangePayload {
 export function isInRange({ min, max }: IsInRangePayload, error?: React.ReactNode) {
   const _error = error || true;
 
-  return (value: unknown) => {
+  return (value: unknown): React.ReactNode => {
     if (typeof value !== 'number') {
       return _error;
     }
diff --git a/packages/@mantine/form/src/validators/is-not-empty/is-not-empty.ts b/packages/@mantine/form/src/validators/is-not-empty/is-not-empty.ts
index f61a7d1cc6f..402a84c4945 100644
--- a/packages/@mantine/form/src/validators/is-not-empty/is-not-empty.ts
+++ b/packages/@mantine/form/src/validators/is-not-empty/is-not-empty.ts
@@ -1,7 +1,7 @@
 export function isNotEmpty(error?: React.ReactNode) {
   const _error = error || true;
 
-  return (value: unknown) => {
+  return (value: unknown): React.ReactNode => {
     if (typeof value === 'string') {
       return value.trim().length > 0 ? null : _error;
     }
diff --git a/packages/@mantine/form/src/validators/matches-field/matches-field.ts b/packages/@mantine/form/src/validators/matches-field/matches-field.ts
index 6cf7206ac2d..216a586c5cd 100644
--- a/packages/@mantine/form/src/validators/matches-field/matches-field.ts
+++ b/packages/@mantine/form/src/validators/matches-field/matches-field.ts
@@ -1,7 +1,7 @@
 export function matchesField(field: string, error?: React.ReactNode) {
   const _error = error || true;
 
-  return (value: unknown, values: Record<string, unknown>) => {
+  return (value: unknown, values: Record<string, unknown>): React.ReactNode => {
     if (!values || !(field in values)) {
       return _error;
     }
diff --git a/packages/@mantine/form/src/validators/matches/matches.ts b/packages/@mantine/form/src/validators/matches/matches.ts
index 2b739aabb49..09ce85045d9 100644
--- a/packages/@mantine/form/src/validators/matches/matches.ts
+++ b/packages/@mantine/form/src/validators/matches/matches.ts
@@ -1,7 +1,7 @@
 export function matches(regexp: RegExp, error?: React.ReactNode) {
   const _error = error || true;
 
-  return (value: unknown) => {
+  return (value: unknown): React.ReactNode => {
     if (typeof value !== 'string') {
       return _error;
     }