diff --git a/gqlgen.yml b/gqlgen.yml
index 8ec8478..bd51335 100755
--- a/gqlgen.yml
+++ b/gqlgen.yml
@@ -15,6 +15,8 @@ resolver:
   package: resolvers
   filename_template: "{name}.go"
 
+nullable_input_omittable: true
+
 autobind:
   - github.com/avptp/brain/internal/generated/data
 
diff --git a/internal/api/arguments/main.go b/internal/api/arguments/main.go
deleted file mode 100644
index 10b30bb..0000000
--- a/internal/api/arguments/main.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package arguments
-
-import (
-	"context"
-
-	"github.com/99designs/gqlgen/graphql"
-)
-
-func GetFields(ctx context.Context, name string) []string {
-	fieldContext := graphql.GetFieldContext(ctx)
-
-	names := []string{}
-
-	for _, arg := range fieldContext.Field.Arguments {
-		if arg.Name != name {
-			continue
-		}
-
-		for _, child := range arg.Value.Children {
-			names = append(names, child.Name)
-		}
-	}
-
-	return names
-}
diff --git a/internal/api/resolvers/person.go b/internal/api/resolvers/person.go
index 8c54e9a..34d5812 100755
--- a/internal/api/resolvers/person.go
+++ b/internal/api/resolvers/person.go
@@ -9,7 +9,6 @@ import (
 
 	"entgo.io/contrib/entgql"
 	"github.com/alexedwards/argon2id"
-	"github.com/avptp/brain/internal/api/arguments"
 	"github.com/avptp/brain/internal/api/reporting"
 	"github.com/avptp/brain/internal/auth"
 	"github.com/avptp/brain/internal/generated/api"
@@ -29,15 +28,19 @@ func (r *mutationResolver) CreatePerson(ctx context.Context, input api.CreatePer
 	d := data.FromContext(ctx) // transactional data client for mutations
 	allowCtx := privacy.DecisionContext(ctx, privacy.Allow)
 
-	p, err := d.Person.
+	create := d.Person.
 		Create().
 		SetEmail(input.Email).
 		SetPassword(input.Password).
 		SetTaxID(input.TaxID).
 		SetFirstName(input.FirstName).
-		SetNillableLastName(input.LastName).
-		SetLanguage(input.Language).
-		Save(allowCtx)
+		SetLanguage(input.Language)
+
+	if input.LastName.IsSet() {
+		create.SetNillableLastName(input.LastName.Value())
+	}
+
+	p, err := create.Save(allowCtx)
 
 	if err != nil {
 		return nil, err
@@ -53,77 +56,91 @@ func (r *mutationResolver) UpdatePerson(ctx context.Context, input api.UpdatePer
 	d := data.FromContext(ctx) // transactional data client for mutations
 	update := d.Person.UpdateOneID(input.ID)
 
-	// This is not clean, but it is an option until "gqlgen" makes it
-	// possible to distinguish between undefined and null fields.
-	// See: https://github.com/99designs/gqlgen/issues/1416
-	fields := arguments.GetFields(ctx, "input")
-
-	for _, key := range fields {
-		switch key {
-		case "email":
-			if v := input.Email; v != nil {
-				update.SetEmail(*v)
-			}
-		case "phone":
-			if v := input.Phone; v != nil {
-				update.SetPhone(*v)
-			} else {
-				update.ClearPhone()
-			}
-		case "taxId":
-			if v := input.TaxID; v != nil {
-				update.SetTaxID(*v)
-			}
-		case "firstName":
-			if v := input.FirstName; v != nil {
-				update.SetFirstName(*v)
-			}
-		case "lastName":
-			if v := input.LastName; v != nil {
-				update.SetLastName(*v)
-			} else {
-				update.ClearLastName()
-			}
-		case "language":
-			if v := input.Language; v != nil {
-				update.SetLanguage(*v)
-			}
-		case "birthdate":
-			if v := input.Birthdate; v != nil {
-				update.SetBirthdate(*v)
-			} else {
-				update.ClearBirthdate()
-			}
-		case "gender":
-			if v := input.Gender; v != nil {
-				update.SetGender(*v)
-			} else {
-				update.ClearGender()
-			}
-		case "address":
-			if v := input.Address; v != nil {
-				update.SetAddress(*v)
-			} else {
-				update.ClearAddress()
-			}
-		case "postalCode":
-			if v := input.PostalCode; v != nil {
-				update.SetPostalCode(*v)
-			} else {
-				update.ClearPostalCode()
-			}
-		case "city":
-			if v := input.City; v != nil {
-				update.SetCity(*v)
-			} else {
-				update.ClearCity()
-			}
-		case "country":
-			if v := input.Country; v != nil {
-				update.SetCountry(*v)
-			} else {
-				update.ClearCountry()
-			}
+	if input.Email.IsSet() {
+		if v := input.Email.Value(); v != nil {
+			update.SetEmail(*v)
+		}
+	}
+
+	if input.Phone.IsSet() {
+		if v := input.Phone.Value(); v != nil {
+			update.SetPhone(*v)
+		} else {
+			update.ClearPhone()
+		}
+	}
+
+	if input.TaxID.IsSet() {
+		if v := input.TaxID.Value(); v != nil {
+			update.SetTaxID(*v)
+		}
+	}
+
+	if input.FirstName.IsSet() {
+		if v := input.FirstName.Value(); v != nil {
+			update.SetFirstName(*v)
+		}
+	}
+
+	if input.LastName.IsSet() {
+		if v := input.LastName.Value(); v != nil {
+			update.SetLastName(*v)
+		} else {
+			update.ClearLastName()
+		}
+	}
+
+	if input.Language.IsSet() {
+		if v := input.Language.Value(); v != nil {
+			update.SetLanguage(*v)
+		}
+	}
+
+	if input.Birthdate.IsSet() {
+		if v := input.Birthdate.Value(); v != nil {
+			update.SetBirthdate(*v)
+		} else {
+			update.ClearBirthdate()
+		}
+	}
+
+	if input.Gender.IsSet() {
+		if v := input.Gender.Value(); v != nil {
+			update.SetGender(*v)
+		} else {
+			update.ClearGender()
+		}
+	}
+
+	if input.Address.IsSet() {
+		if v := input.Address.Value(); v != nil {
+			update.SetAddress(*v)
+		} else {
+			update.ClearAddress()
+		}
+	}
+
+	if input.PostalCode.IsSet() {
+		if v := input.PostalCode.Value(); v != nil {
+			update.SetPostalCode(*v)
+		} else {
+			update.ClearPostalCode()
+		}
+	}
+
+	if input.City.IsSet() {
+		if v := input.City.Value(); v != nil {
+			update.SetCity(*v)
+		} else {
+			update.ClearCity()
+		}
+	}
+
+	if input.Country.IsSet() {
+		if v := input.Country.Value(); v != nil {
+			update.SetCountry(*v)
+		} else {
+			update.ClearCountry()
 		}
 	}
 
diff --git a/internal/generated/api/exec.go b/internal/generated/api/exec.go
index e8c12d6..65e7fa6 100644
--- a/internal/generated/api/exec.go
+++ b/internal/generated/api/exec.go
@@ -5286,7 +5286,7 @@ func (ec *executionContext) unmarshalInputCreatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.LastName = data
+			it.LastName = graphql.OmittableOf(data)
 		case "language":
 			var err error
 
@@ -5418,7 +5418,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Email = data
+			it.Email = graphql.OmittableOf(data)
 		case "phone":
 			var err error
 
@@ -5427,7 +5427,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Phone = data
+			it.Phone = graphql.OmittableOf(data)
 		case "taxId":
 			var err error
 
@@ -5436,7 +5436,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.TaxID = data
+			it.TaxID = graphql.OmittableOf(data)
 		case "firstName":
 			var err error
 
@@ -5445,7 +5445,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.FirstName = data
+			it.FirstName = graphql.OmittableOf(data)
 		case "lastName":
 			var err error
 
@@ -5454,7 +5454,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.LastName = data
+			it.LastName = graphql.OmittableOf(data)
 		case "language":
 			var err error
 
@@ -5463,7 +5463,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Language = data
+			it.Language = graphql.OmittableOf(data)
 		case "birthdate":
 			var err error
 
@@ -5472,7 +5472,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Birthdate = data
+			it.Birthdate = graphql.OmittableOf(data)
 		case "gender":
 			var err error
 
@@ -5481,7 +5481,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Gender = data
+			it.Gender = graphql.OmittableOf(data)
 		case "address":
 			var err error
 
@@ -5490,7 +5490,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Address = data
+			it.Address = graphql.OmittableOf(data)
 		case "postalCode":
 			var err error
 
@@ -5499,7 +5499,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.PostalCode = data
+			it.PostalCode = graphql.OmittableOf(data)
 		case "city":
 			var err error
 
@@ -5508,7 +5508,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.City = data
+			it.City = graphql.OmittableOf(data)
 		case "country":
 			var err error
 
@@ -5517,7 +5517,7 @@ func (ec *executionContext) unmarshalInputUpdatePersonInput(ctx context.Context,
 			if err != nil {
 				return it, err
 			}
-			it.Country = data
+			it.Country = graphql.OmittableOf(data)
 		}
 	}
 
diff --git a/internal/generated/api/model.go b/internal/generated/api/model.go
index 261f601..c0db10a 100644
--- a/internal/generated/api/model.go
+++ b/internal/generated/api/model.go
@@ -5,6 +5,7 @@ package api
 import (
 	"time"
 
+	"github.com/99designs/gqlgen/graphql"
 	"github.com/avptp/brain/internal/generated/data"
 	"github.com/avptp/brain/internal/generated/data/person"
 	"github.com/google/uuid"
@@ -20,13 +21,13 @@ type CreateAuthenticationPayload struct {
 }
 
 type CreatePersonInput struct {
-	Email     string  `json:"email"`
-	Password  string  `json:"password"`
-	TaxID     string  `json:"taxId"`
-	FirstName string  `json:"firstName"`
-	LastName  *string `json:"lastName,omitempty"`
-	Language  string  `json:"language"`
-	Captcha   string  `json:"captcha"`
+	Email     string                     `json:"email"`
+	Password  string                     `json:"password"`
+	TaxID     string                     `json:"taxId"`
+	FirstName string                     `json:"firstName"`
+	LastName  graphql.Omittable[*string] `json:"lastName,omitempty"`
+	Language  string                     `json:"language"`
+	Captcha   string                     `json:"captcha"`
 }
 
 type CreatePersonPayload struct {
@@ -52,19 +53,19 @@ type DeletePersonPayload struct {
 }
 
 type UpdatePersonInput struct {
-	ID         uuid.UUID      `json:"id"`
-	Email      *string        `json:"email,omitempty"`
-	Phone      *string        `json:"phone,omitempty"`
-	TaxID      *string        `json:"taxId,omitempty"`
-	FirstName  *string        `json:"firstName,omitempty"`
-	LastName   *string        `json:"lastName,omitempty"`
-	Language   *string        `json:"language,omitempty"`
-	Birthdate  *time.Time     `json:"birthdate,omitempty"`
-	Gender     *person.Gender `json:"gender,omitempty"`
-	Address    *string        `json:"address,omitempty"`
-	PostalCode *string        `json:"postalCode,omitempty"`
-	City       *string        `json:"city,omitempty"`
-	Country    *string        `json:"country,omitempty"`
+	ID         uuid.UUID                         `json:"id"`
+	Email      graphql.Omittable[*string]        `json:"email,omitempty"`
+	Phone      graphql.Omittable[*string]        `json:"phone,omitempty"`
+	TaxID      graphql.Omittable[*string]        `json:"taxId,omitempty"`
+	FirstName  graphql.Omittable[*string]        `json:"firstName,omitempty"`
+	LastName   graphql.Omittable[*string]        `json:"lastName,omitempty"`
+	Language   graphql.Omittable[*string]        `json:"language,omitempty"`
+	Birthdate  graphql.Omittable[*time.Time]     `json:"birthdate,omitempty"`
+	Gender     graphql.Omittable[*person.Gender] `json:"gender,omitempty"`
+	Address    graphql.Omittable[*string]        `json:"address,omitempty"`
+	PostalCode graphql.Omittable[*string]        `json:"postalCode,omitempty"`
+	City       graphql.Omittable[*string]        `json:"city,omitempty"`
+	Country    graphql.Omittable[*string]        `json:"country,omitempty"`
 }
 
 type UpdatePersonPasswordInput struct {