diff --git a/internal/code/models.go b/internal/code/models.go
index b321456..094efa0 100644
--- a/internal/code/models.go
+++ b/internal/code/models.go
@@ -88,6 +88,11 @@ func (intf InterfaceType) Code() string {
 	return `interface{}`
 }
 
+// IsNumber returns false
+func (intf InterfaceType) IsNumber() bool {
+	return false
+}
+
 // Method is a definition of the method inside the interface
 type Method struct {
 	Name    string
@@ -104,6 +109,7 @@ type Param struct {
 // Type is an interface for value types
 type Type interface {
 	Code() string
+	IsNumber() bool
 }
 
 // SimpleType is a type that can be called directly
@@ -114,6 +120,13 @@ func (t SimpleType) Code() string {
 	return string(t)
 }
 
+// IsNumber returns true id a SimpleType is integer or float variants.
+func (t SimpleType) IsNumber() bool {
+	return t == "uint" || t == "uint8" || t == "uint16" || t == "uint32" || t == "uint64" ||
+		t == "int" || t == "int8" || t == "int16" || t == "int32" || t == "int64" ||
+		t == "float32" || t == "float64"
+}
+
 // ExternalType is a type that is called to another package
 type ExternalType struct {
 	PackageAlias string
@@ -125,6 +138,11 @@ func (t ExternalType) Code() string {
 	return fmt.Sprintf("%s.%s", t.PackageAlias, t.Name)
 }
 
+// IsNumber returns false
+func (t ExternalType) IsNumber() bool {
+	return false
+}
+
 // PointerType is a model of pointer
 type PointerType struct {
 	ContainedType Type
@@ -135,6 +153,11 @@ func (t PointerType) Code() string {
 	return fmt.Sprintf("*%s", t.ContainedType.Code())
 }
 
+// IsNumber returns IsNumber of its contained type
+func (t PointerType) IsNumber() bool {
+	return t.ContainedType.IsNumber()
+}
+
 // ArrayType is a model of array
 type ArrayType struct {
 	ContainedType Type
@@ -144,3 +167,8 @@ type ArrayType struct {
 func (t ArrayType) Code() string {
 	return fmt.Sprintf("[]%s", t.ContainedType.Code())
 }
+
+// IsNumber returns false
+func (t ArrayType) IsNumber() bool {
+	return false
+}
diff --git a/internal/code/models_test.go b/internal/code/models_test.go
index 8ad7ab8..66b6f54 100644
--- a/internal/code/models_test.go
+++ b/internal/code/models_test.go
@@ -92,7 +92,7 @@ type TypeCodeTestCase struct {
 	ExpectedCode string
 }
 
-func TestArrayTypeCode(t *testing.T) {
+func TestTypeCode(t *testing.T) {
 	testTable := []TypeCodeTestCase{
 		{
 			Name:         "simple type",
@@ -126,3 +126,89 @@ func TestArrayTypeCode(t *testing.T) {
 		})
 	}
 }
+
+type TypeIsNumberTestCase struct {
+	Name     string
+	Type     code.Type
+	IsNumber bool
+}
+
+func TestTypeIsNumber(t *testing.T) {
+	testTable := []TypeIsNumberTestCase{
+		{
+			Name:     "simple type: int",
+			Type:     code.SimpleType("int"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: other integer variants",
+			Type:     code.SimpleType("int64"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: uint",
+			Type:     code.SimpleType("uint"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: other unsigned integer variants",
+			Type:     code.SimpleType("uint64"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: float32",
+			Type:     code.SimpleType("float32"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: other float variants",
+			Type:     code.SimpleType("float64"),
+			IsNumber: true,
+		},
+		{
+			Name:     "simple type: non-number primitive type",
+			Type:     code.SimpleType("string"),
+			IsNumber: false,
+		},
+		{
+			Name:     "simple type: non-number custom type",
+			Type:     code.SimpleType("UserModel"),
+			IsNumber: false,
+		},
+		{
+			Name:     "external type",
+			Type:     code.ExternalType{PackageAlias: "context", Name: "Context"},
+			IsNumber: false,
+		},
+		{
+			Name:     "pointer type: number",
+			Type:     code.PointerType{ContainedType: code.SimpleType("int")},
+			IsNumber: true,
+		},
+		{
+			Name:     "pointer type: non-number",
+			Type:     code.PointerType{ContainedType: code.SimpleType("string")},
+			IsNumber: false,
+		},
+		{
+			Name:     "array type",
+			Type:     code.ArrayType{ContainedType: code.SimpleType("int")},
+			IsNumber: false,
+		},
+		{
+			Name:     "interface type",
+			Type:     code.InterfaceType{},
+			IsNumber: false,
+		},
+	}
+
+	for _, testCase := range testTable {
+		t.Run(testCase.Name, func(t *testing.T) {
+			isNumber := testCase.Type.IsNumber()
+
+			if isNumber != testCase.IsNumber {
+				t.Errorf("Expected = %+v\nReceived = %+v", testCase.IsNumber, isNumber)
+			}
+		})
+	}
+}
diff --git a/internal/mongo/generator.go b/internal/mongo/generator.go
index d128197..bde2b5a 100644
--- a/internal/mongo/generator.go
+++ b/internal/mongo/generator.go
@@ -122,8 +122,8 @@ func (g RepositoryGenerator) generateFindImplementation(operation spec.FindOpera
 	return generateFromTemplate("mongo_repository_findmany", findManyTemplate, tmplData)
 }
 
-func (g RepositoryGenerator) mongoSorts(sortSpec []spec.Sort) ([]sort, error) {
-	var sorts []sort
+func (g RepositoryGenerator) mongoSorts(sortSpec []spec.Sort) ([]findSort, error) {
+	var sorts []findSort
 
 	for _, s := range sortSpec {
 		bsonFieldReference, err := g.bsonFieldReference(s.FieldReference)
@@ -131,7 +131,7 @@ func (g RepositoryGenerator) mongoSorts(sortSpec []spec.Sort) ([]sort, error) {
 			return nil, err
 		}
 
-		sorts = append(sorts, sort{
+		sorts = append(sorts, findSort{
 			BsonTag:  bsonFieldReference,
 			Ordering: s.Ordering,
 		})
@@ -196,6 +196,8 @@ func getUpdateOperatorKey(operator spec.UpdateOperator) string {
 		return "$set"
 	case spec.UpdateOperatorPush:
 		return "$push"
+	case spec.UpdateOperatorInc:
+		return "$inc"
 	default:
 		return ""
 	}
diff --git a/internal/mongo/generator_test.go b/internal/mongo/generator_test.go
index b72d7ae..d35a57e 100644
--- a/internal/mongo/generator_test.go
+++ b/internal/mongo/generator_test.go
@@ -1063,7 +1063,7 @@ func (r *UserRepositoryMongo) UpdateAgeByGender(arg0 context.Context, arg1 int,
 				Params: []code.Param{
 					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
 					{Name: "consentHistory", Type: code.SimpleType("ConsentHistory")},
-					{Name: "gender", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
+					{Name: "id", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
 				},
 				Returns: []code.Type{
 					code.SimpleType("bool"),
@@ -1095,6 +1095,47 @@ func (r *UserRepositoryMongo) UpdateConsentHistoryPushByID(arg0 context.Context,
 	}
 	return result.MatchedCount > 0, err
 }
+`,
+		},
+		{
+			Name: "simple update inc method",
+			MethodSpec: spec.MethodSpec{
+				Name: "UpdateAgeIncByID",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "age", Type: code.SimpleType("int")},
+					{Name: "id", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
+				},
+				Returns: []code.Type{
+					code.SimpleType("bool"),
+					code.SimpleType("error"),
+				},
+				Operation: spec.UpdateOperation{
+					Update: spec.UpdateFields{
+						{FieldReference: spec.FieldReference{ageField}, ParamIndex: 1, Operator: spec.UpdateOperatorInc},
+					},
+					Mode: spec.QueryModeOne,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{FieldReference: spec.FieldReference{idField}, Comparator: spec.ComparatorEqual, ParamIndex: 2},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
+func (r *UserRepositoryMongo) UpdateAgeIncByID(arg0 context.Context, arg1 int, arg2 primitive.ObjectID) (bool, error) {
+	result, err := r.collection.UpdateOne(arg0, bson.M{
+		"_id": arg2,
+	}, bson.M{
+		"$inc": bson.M{
+			"age": arg1,
+		},
+	})
+	if err != nil {
+		return false, err
+	}
+	return result.MatchedCount > 0, err
+}
 `,
 		},
 		{
@@ -1129,12 +1170,12 @@ func (r *UserRepositoryMongo) UpdateEnabledAndConsentHistoryPushByID(arg0 contex
 	result, err := r.collection.UpdateOne(arg0, bson.M{
 		"_id": arg3,
 	}, bson.M{
-		"$set": bson.M{
-			"enabled": arg1,
-		},
 		"$push": bson.M{
 			"consent_history": arg2,
 		},
+		"$set": bson.M{
+			"enabled": arg1,
+		},
 	})
 	if err != nil {
 		return false, err
diff --git a/internal/mongo/models.go b/internal/mongo/models.go
index 807b393..1f12a58 100644
--- a/internal/mongo/models.go
+++ b/internal/mongo/models.go
@@ -2,6 +2,7 @@ package mongo
 
 import (
 	"fmt"
+	"sort"
 	"strings"
 
 	"github.com/sunboyy/repogen/internal/spec"
@@ -26,11 +27,17 @@ func (u updateModel) Code() string {
 type updateFields map[string][]updateField
 
 func (u updateFields) Code() string {
-	var lines []string
-	for k, v := range u {
-		lines = append(lines, fmt.Sprintf(`		"%s": bson.M{`, k))
+	var keys []string
+	for k := range u {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
 
-		for _, field := range v {
+	var lines []string
+	for _, key := range keys {
+		lines = append(lines, fmt.Sprintf(`		"%s": bson.M{`, key))
+
+		for _, field := range u[key] {
 			lines = append(lines, fmt.Sprintf(`			"%s": arg%d,`, field.BsonTag, field.ParamIndex))
 		}
 
diff --git a/internal/mongo/templates.go b/internal/mongo/templates.go
index a00feb8..da3112e 100644
--- a/internal/mongo/templates.go
+++ b/internal/mongo/templates.go
@@ -91,15 +91,15 @@ const insertManyTemplate = `	var entities []interface{}
 type mongoFindTemplateData struct {
 	EntityType string
 	QuerySpec  querySpec
-	Sorts      []sort
+	Sorts      []findSort
 }
 
-type sort struct {
+type findSort struct {
 	BsonTag  string
 	Ordering spec.Ordering
 }
 
-func (s sort) OrderNum() int {
+func (s findSort) OrderNum() int {
 	if s.Ordering == spec.OrderingAscending {
 		return 1
 	}
diff --git a/internal/spec/errors.go b/internal/spec/errors.go
index 40f987f..7580991 100644
--- a/internal/spec/errors.go
+++ b/internal/spec/errors.go
@@ -22,8 +22,6 @@ func (err ParsingError) Error() string {
 		return "update fields are invalid"
 	case ContextParamRequiredError:
 		return "context parameter is required"
-	case PushNonArrayError:
-		return "cannot use push operation in a non-array type"
 	}
 	return string(err)
 }
@@ -35,7 +33,6 @@ const (
 	InvalidParamError         ParsingError = "ERROR_INVALID_PARAM"
 	InvalidUpdateFieldsError  ParsingError = "ERROR_INVALID_UPDATE_FIELDS"
 	ContextParamRequiredError ParsingError = "ERROR_CONTEXT_PARAM_REQUIRED"
-	PushNonArrayError         ParsingError = "ERROR_PUSH_NON_ARRAY"
 )
 
 // NewInvalidQueryError creates invalidQueryError
@@ -64,6 +61,26 @@ func (err invalidSortError) Error() string {
 	return fmt.Sprintf("invalid sort '%s'", err.SortString)
 }
 
+// NewArgumentTypeNotMatchedError creates argumentTypeNotMatchedError
+func NewArgumentTypeNotMatchedError(fieldName string, requiredType code.Type, givenType code.Type) error {
+	return argumentTypeNotMatchedError{
+		FieldName:    fieldName,
+		RequiredType: requiredType,
+		GivenType:    givenType,
+	}
+}
+
+type argumentTypeNotMatchedError struct {
+	FieldName    string
+	RequiredType code.Type
+	GivenType    code.Type
+}
+
+func (err argumentTypeNotMatchedError) Error() string {
+	return fmt.Sprintf("field '%s' requires an argument of type '%s' (got '%s')",
+		err.FieldName, err.RequiredType.Code(), err.GivenType.Code())
+}
+
 // NewUnknownOperationError creates unknownOperationError
 func NewUnknownOperationError(operationName string) error {
 	return unknownOperationError{OperationName: operationName}
@@ -107,3 +124,23 @@ func (err incompatibleComparatorError) Error() string {
 	return fmt.Sprintf("cannot use comparator %s with struct field '%s' of type '%s'",
 		err.Comparator, err.Field.Name, err.Field.Type.Code())
 }
+
+// NewIncompatibleUpdateOperatorError creates incompatibleUpdateOperatorError
+func NewIncompatibleUpdateOperatorError(updateOperator UpdateOperator, fieldReference FieldReference) error {
+	return incompatibleUpdateOperatorError{
+		UpdateOperator:  updateOperator,
+		ReferencingCode: fieldReference.ReferencingCode(),
+		ReferencedType:  fieldReference.ReferencedField().Type,
+	}
+}
+
+type incompatibleUpdateOperatorError struct {
+	UpdateOperator  UpdateOperator
+	ReferencingCode string
+	ReferencedType  code.Type
+}
+
+func (err incompatibleUpdateOperatorError) Error() string {
+	return fmt.Sprintf("cannot use update operator %s with struct field '%s' of type '%s'",
+		err.UpdateOperator, err.ReferencingCode, err.ReferencedType.Code())
+}
diff --git a/internal/spec/errors_test.go b/internal/spec/errors_test.go
index 0fe35a4..8d7423f 100644
--- a/internal/spec/errors_test.go
+++ b/internal/spec/errors_test.go
@@ -43,6 +43,19 @@ func TestError(t *testing.T) {
 			Error:          spec.NewInvalidSortError([]string{"Order", "By"}),
 			ExpectedString: "invalid sort 'OrderBy'",
 		},
+		{
+			Name:           "ArgumentTypeNotMatchedError",
+			Error:          spec.NewArgumentTypeNotMatchedError("Age", code.SimpleType("int"), code.SimpleType("float64")),
+			ExpectedString: "field 'Age' requires an argument of type 'int' (got 'float64')",
+		},
+		{
+			Name: "IncompatibleUpdateOperatorError",
+			Error: spec.NewIncompatibleUpdateOperatorError(spec.UpdateOperatorInc, spec.FieldReference{{
+				Name: "City",
+				Type: code.SimpleType("string"),
+			}}),
+			ExpectedString: "cannot use update operator INC with struct field 'City' of type 'string'",
+		},
 	}
 
 	for _, testCase := range testTable {
diff --git a/internal/spec/field.go b/internal/spec/field.go
index 4689371..2532cba 100644
--- a/internal/spec/field.go
+++ b/internal/spec/field.go
@@ -14,6 +14,15 @@ func (r FieldReference) ReferencedField() code.StructField {
 	return r[len(r)-1]
 }
 
+// ReferencingCode returns a string containing name of the referenced fields concatenating with period (.).
+func (r FieldReference) ReferencingCode() string {
+	var fieldNames []string
+	for _, field := range r {
+		fieldNames = append(fieldNames, field.Name)
+	}
+	return strings.Join(fieldNames, ".")
+}
+
 type fieldResolver struct {
 	Structs code.Structs
 }
diff --git a/internal/spec/parser.go b/internal/spec/parser.go
index 1d74b1e..45a3b6b 100644
--- a/internal/spec/parser.go
+++ b/internal/spec/parser.go
@@ -381,9 +381,11 @@ func (p interfaceMethodParser) validateQueryFromParams(params []code.Param, quer
 		}
 
 		for i := 0; i < predicate.Comparator.NumberOfArguments(); i++ {
-			if params[currentParamIndex].Type != predicate.Comparator.ArgumentTypeFromFieldType(
-				predicate.FieldReference.ReferencedField().Type) {
-				return InvalidParamError
+			requiredType := predicate.Comparator.ArgumentTypeFromFieldType(predicate.FieldReference.ReferencedField().Type)
+
+			if params[currentParamIndex].Type != requiredType {
+				return NewArgumentTypeNotMatchedError(predicate.FieldReference.ReferencingCode(), requiredType,
+					params[currentParamIndex].Type)
 			}
 			currentParamIndex++
 		}
diff --git a/internal/spec/parser_test.go b/internal/spec/parser_test.go
index d97eb81..3bc84c2 100644
--- a/internal/spec/parser_test.go
+++ b/internal/spec/parser_test.go
@@ -811,6 +811,30 @@ func TestParseInterfaceMethod_Update(t *testing.T) {
 				}},
 			},
 		},
+		{
+			Name: "UpdateArgPushByArg method",
+			Method: code.Method{
+				Name: "UpdateAgeIncByID",
+				Params: []code.Param{
+					{Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Type: code.SimpleType("int")},
+					{Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
+				},
+				Returns: []code.Type{
+					code.SimpleType("bool"),
+					code.SimpleType("error"),
+				},
+			},
+			ExpectedOperation: spec.UpdateOperation{
+				Update: spec.UpdateFields{
+					{FieldReference: spec.FieldReference{ageField}, ParamIndex: 1, Operator: spec.UpdateOperatorInc},
+				},
+				Mode: spec.QueryModeOne,
+				Query: spec.QuerySpec{Predicates: []spec.Predicate{
+					{FieldReference: spec.FieldReference{idField}, Comparator: spec.ComparatorEqual, ParamIndex: 2},
+				}},
+			},
+		},
 		{
 			Name: "UpdateArgAndArgPushByArg method",
 			Method: code.Method{
@@ -1564,7 +1588,7 @@ func TestParseInterfaceMethod_Find_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError(genderField.Name, genderField.Type, code.SimpleType("string")),
 		},
 		{
 			Name: "mismatched method parameter type for special case",
@@ -1579,7 +1603,8 @@ func TestParseInterfaceMethod_Find_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError(cityField.Name,
+				code.ArrayType{ContainedType: code.SimpleType("string")}, code.SimpleType("string")),
 		},
 		{
 			Name: "misplaced operator token (leftmost)",
@@ -1716,7 +1741,29 @@ func TestParseInterfaceMethod_Update_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.PushNonArrayError,
+			ExpectedError: spec.NewIncompatibleUpdateOperatorError(spec.UpdateOperatorPush, spec.FieldReference{{
+				Name: "Gender",
+				Type: code.SimpleType("Gender"),
+			}}),
+		},
+		{
+			Name: "inc operator in non-number field",
+			Method: code.Method{
+				Name: "UpdateCityIncByID",
+				Params: []code.Param{
+					{Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Type: code.SimpleType("Gender")},
+					{Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
+				},
+				Returns: []code.Type{
+					code.SimpleType("bool"),
+					code.SimpleType("error"),
+				},
+			},
+			ExpectedError: spec.NewIncompatibleUpdateOperatorError(spec.UpdateOperatorInc, spec.FieldReference{{
+				Name: "City",
+				Type: code.SimpleType("string"),
+			}}),
 		},
 		{
 			Name: "update method without query",
@@ -1762,7 +1809,8 @@ func TestParseInterfaceMethod_Update_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidUpdateFieldsError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError(consentHistoryField.Name, code.SimpleType("ConsentHistoryItem"),
+				code.ArrayType{ContainedType: code.SimpleType("ConsentHistoryItem")}),
 		},
 		{
 			Name: "insufficient function parameters",
@@ -1839,7 +1887,7 @@ func TestParseInterfaceMethod_Update_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidUpdateFieldsError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError(ageField.Name, ageField.Type, code.SimpleType("float64")),
 		},
 		{
 			Name: "struct field does not match parameter in query",
@@ -1855,7 +1903,7 @@ func TestParseInterfaceMethod_Update_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError(genderField.Name, genderField.Type, code.SimpleType("string")),
 		},
 	}
 
@@ -2019,7 +2067,7 @@ func TestParseInterfaceMethod_Delete_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError("Gender", code.SimpleType("Gender"), code.SimpleType("string")),
 		},
 		{
 			Name: "mismatched method parameter type for special case",
@@ -2034,7 +2082,8 @@ func TestParseInterfaceMethod_Delete_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError("City",
+				code.ArrayType{ContainedType: code.SimpleType("string")}, code.SimpleType("string")),
 		},
 	}
 
@@ -2150,7 +2199,7 @@ func TestParseInterfaceMethod_Count_Invalid(t *testing.T) {
 					code.SimpleType("error"),
 				},
 			},
-			ExpectedError: spec.InvalidParamError,
+			ExpectedError: spec.NewArgumentTypeNotMatchedError("Gender", code.SimpleType("Gender"), code.SimpleType("string")),
 		},
 		{
 			Name: "struct field not found",
diff --git a/internal/spec/update.go b/internal/spec/update.go
index ba9338d..245807a 100644
--- a/internal/spec/update.go
+++ b/internal/spec/update.go
@@ -61,6 +61,7 @@ type UpdateOperator string
 const (
 	UpdateOperatorSet  UpdateOperator = "SET"
 	UpdateOperatorPush UpdateOperator = "PUSH"
+	UpdateOperatorInc  UpdateOperator = "INC"
 )
 
 // NumberOfArguments returns number of arguments required to perform an update operation
@@ -69,16 +70,13 @@ func (o UpdateOperator) NumberOfArguments() int {
 }
 
 // ArgumentType returns type that is required for function parameter
-func (o UpdateOperator) ArgumentType(fieldType code.Type) (code.Type, error) {
+func (o UpdateOperator) ArgumentType(fieldType code.Type) code.Type {
 	switch o {
 	case UpdateOperatorPush:
-		arrayType, ok := fieldType.(code.ArrayType)
-		if !ok {
-			return nil, PushNonArrayError
-		}
-		return arrayType.ContainedType, nil
+		arrayType := fieldType.(code.ArrayType)
+		return arrayType.ContainedType
 	default:
-		return fieldType, nil
+		return fieldType
 	}
 }
 
@@ -147,14 +145,12 @@ func (p interfaceMethodParser) parseUpdate(tokens []string) (Update, error) {
 			return nil, InvalidUpdateFieldsError
 		}
 
-		requiredType, err := field.Operator.ArgumentType(field.FieldReference.ReferencedField().Type)
-		if err != nil {
-			return nil, err
-		}
+		requiredType := field.Operator.ArgumentType(field.FieldReference.ReferencedField().Type)
 
 		for i := 0; i < field.Operator.NumberOfArguments(); i++ {
 			if requiredType != p.Method.Params[field.ParamIndex+i].Type {
-				return nil, InvalidUpdateFieldsError
+				return nil, NewArgumentTypeNotMatchedError(field.FieldReference.ReferencingCode(), requiredType,
+					p.Method.Params[field.ParamIndex+i].Type)
 			}
 		}
 	}
@@ -166,6 +162,9 @@ func (p interfaceMethodParser) parseUpdateField(t []string, paramIndex int) (Upd
 	if len(t) > 1 && t[len(t)-1] == "Push" {
 		return p.createUpdateField(t[:len(t)-1], UpdateOperatorPush, paramIndex)
 	}
+	if len(t) > 1 && t[len(t)-1] == "Inc" {
+		return p.createUpdateField(t[:len(t)-1], UpdateOperatorInc, paramIndex)
+	}
 	return p.createUpdateField(t, UpdateOperatorSet, paramIndex)
 }
 
@@ -175,9 +174,24 @@ func (p interfaceMethodParser) createUpdateField(t []string, operator UpdateOper
 		return UpdateField{}, NewStructFieldNotFoundError(t)
 	}
 
+	if !p.validateUpdateOperator(fieldReference.ReferencedField().Type, operator) {
+		return UpdateField{}, NewIncompatibleUpdateOperatorError(operator, fieldReference)
+	}
+
 	return UpdateField{
 		FieldReference: fieldReference,
 		ParamIndex:     paramIndex,
 		Operator:       operator,
 	}, nil
 }
+
+func (p interfaceMethodParser) validateUpdateOperator(referencedType code.Type, operator UpdateOperator) bool {
+	switch operator {
+	case UpdateOperatorPush:
+		_, ok := referencedType.(code.ArrayType)
+		return ok
+	case UpdateOperatorInc:
+		return referencedType.IsNumber()
+	}
+	return true
+}