diff --git a/check_generics.go b/check_generics.go
index 9d0f3fd..d5573ea 100644
--- a/check_generics.go
+++ b/check_generics.go
@@ -10,7 +10,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"regexp"
 	"runtime"
 	"strings"
 
@@ -194,12 +193,3 @@ func (p *Parser) validLogo(u url.URL) (bool, error) {
 
 	return true, nil
 }
-
-// isMIME checks whether the string in input is a well formed MIME or not.
-func (p *Parser) isMIME(value string) bool {
-	// Regex for MIME.
-	// Reference: https://github.com/jshttp/media-typer/
-	re := regexp.MustCompile("^ *([A-Za-z0-9][A-Za-z0-9!#$&^_-]{0,126})/([A-Za-z0-9][A-Za-z0-9!#$&^_.+-]{0,126}) *$")
-
-	return re.MatchString(value)
-}
diff --git a/keys.go b/keys.go
index 373cd8d..ba3b8ee 100644
--- a/keys.go
+++ b/keys.go
@@ -86,24 +86,10 @@ func (p *Parser) validateFields() error {
 	if len(p.PublicCode.InputTypes) > 0 {
 		vr =  append(vr, ValidationWarning{"inputTypes", "This key is DEPRECATED and will be removed in the future", 0, 0})
 	}
-	for i, mimeType := range p.PublicCode.InputTypes {
-		if !p.isMIME(mimeType) {
-			vr =  append(vr, newValidationError(
-				fmt.Sprintf("inputTypes[%d]", i), "'%s' is not a MIME type", mimeType,
-			))
-		}
-	}
-
 	if len(p.PublicCode.OutputTypes) > 0 {
 		vr =  append(vr, ValidationWarning{"outputTypes", "This key is DEPRECATED and will be removed in the future", 0, 0})
 	}
-	for i, mimeType := range p.PublicCode.OutputTypes {
-		if !p.isMIME(mimeType) {
-			vr =  append(vr, newValidationError(
-				fmt.Sprintf("outputTypes[%d]", i), "'%s' is not a MIME type", mimeType,
-			))
-		}
-	}
+
 
 	for lang, desc := range p.PublicCode.Description {
 		if p.PublicCode.Description == nil {
diff --git a/parser.go b/parser.go
index b72086d..ef6b048 100644
--- a/parser.go
+++ b/parser.go
@@ -238,6 +238,7 @@ func (p *Parser) ParseBytes(in []byte) error {
 			"oneof": "must be one of the following:",
 			"email": "must be a valid email",
 			"date": "must be a date with format 'YYYY-MM-DD'",
+			"is_mime_type": "is not a MIME type",
 			"umax": "must be less or equal than",
 			"umin": "must be more or equal than",
 			"is_category_v0_2": "must be a valid category",
diff --git a/publiccode.go b/publiccode.go
index 6cda4be..bcef259 100644
--- a/publiccode.go
+++ b/publiccode.go
@@ -23,8 +23,8 @@ type PublicCode struct {
 	Logo              string        `yaml:"logo,omitempty"`
 	MonochromeLogo    string        `yaml:"monochromeLogo,omitempty"`
 
-	InputTypes  []string `yaml:"inputTypes,omitempty"`
-	OutputTypes []string `yaml:"outputTypes,omitempty"`
+	InputTypes  []string `yaml:"inputTypes,omitempty" validate:"omitempty,dive,is_mime_type"`
+	OutputTypes []string `yaml:"outputTypes,omitempty" validate:"omitempty,dive,is_mime_type"`
 
 	Platforms []string `yaml:"platforms" validate:"gt=0"`
 
diff --git a/validators/common.go b/validators/common.go
index f6b8ae8..5164375 100644
--- a/validators/common.go
+++ b/validators/common.go
@@ -1,6 +1,7 @@
 package validators;
 
 import (
+	"regexp"
 	"strconv"
 	"time"
 
@@ -40,3 +41,11 @@ func uMin(fl validator.FieldLevel) bool {
 
 	return length >= min
 }
+
+// isMIMEType checks whether the string in input is a well formed MIME type or not.
+func isMIMEType(fl validator.FieldLevel) bool {
+	// Reference: https://github.com/jshttp/media-typer/
+	re := regexp.MustCompile("^ *([A-Za-z0-9][A-Za-z0-9!#$&^_-]{0,126})/([A-Za-z0-9][A-Za-z0-9!#$&^_.+-]{0,126}) *$")
+
+	return re.MatchString(fl.Field().String())
+}
diff --git a/validators/validator.go b/validators/validator.go
index 853a51a..71698c3 100644
--- a/validators/validator.go
+++ b/validators/validator.go
@@ -10,6 +10,7 @@ import (
 func New() *validator.Validate {
 	validate := validator.New()
 	_ = validate.RegisterValidation("date", isDate)
+	_ = validate.RegisterValidation("is_mime_type", isMIMEType)
 	_ = validate.RegisterValidation("iso3166_1_alpha2_lowercase", isIso3166Alpha2Lowercase)
 	_ = validate.RegisterValidation("umax", uMax)
 	_ = validate.RegisterValidation("umin", uMin)