diff --git a/internal/executor/create.go b/internal/executor/create.go
index 7385d03..a9eec1c 100644
--- a/internal/executor/create.go
+++ b/internal/executor/create.go
@@ -173,9 +173,9 @@ func (c *CreateExecutor) createStatus(gtsClient *client.Client) error {
 		return err
 	}
 
-	parsedContentType := model.ParseStatusContentType(c.contentType)
-	if parsedContentType == model.StatusContentTypeUnknown {
-		return InvalidStatusContentTypeError{ContentType: c.contentType}
+	parsedContentType, err := model.ParseStatusContentType(c.contentType)
+	if err != nil {
+		return err
 	}
 
 	form := client.CreateStatusForm{
diff --git a/internal/executor/errors.go b/internal/executor/errors.go
index 54fd190..1a5e6f6 100644
--- a/internal/executor/errors.go
+++ b/internal/executor/errors.go
@@ -58,11 +58,3 @@ func (e EmptyContentError) Error() string {
 
 	return message
 }
-
-type InvalidStatusContentTypeError struct {
-	ContentType string
-}
-
-func (e InvalidStatusContentTypeError) Error() string {
-	return "'" + e.ContentType + "' is an invalid status content type (valid values are plain and markdown)"
-}
diff --git a/internal/model/list.go b/internal/model/list.go
index c4c044e..30f3e48 100644
--- a/internal/model/list.go
+++ b/internal/model/list.go
@@ -95,10 +95,10 @@ type InvalidListRepliesPolicyError struct {
 func (e InvalidListRepliesPolicyError) Error() string {
 	return "'" +
 		e.Value +
-		"' is not a valid list replies policy (valid values are " +
+		"' is not a valid list replies policy: valid values are " +
 		listRepliesPolicyFollowedValue + ", " +
 		listRepliesPolicyListValue + ", " +
-		listRepliesPolicyNoneValue + ")"
+		listRepliesPolicyNoneValue
 }
 
 type List struct {
diff --git a/internal/model/status_content_type.go b/internal/model/status_content_type.go
index 7d33120..8b252a9 100644
--- a/internal/model/status_content_type.go
+++ b/internal/model/status_content_type.go
@@ -38,22 +38,37 @@ func (s StatusContentType) String() string {
 	return output
 }
 
-func ParseStatusContentType(value string) StatusContentType {
+func ParseStatusContentType(value string) (StatusContentType, error) {
 	switch value {
 	case statusContentTypePlainValue, statusContentTypeTextPlainValue:
-		return StatusContentTypePlainText
+		return StatusContentTypePlainText, nil
 	case statusContentTypeMarkdownValue, statusContentTypeTextMarkdownValue:
-		return StatusContentTypeMarkdown
+		return StatusContentTypeMarkdown, nil
 	}
 
-	return StatusContentTypeUnknown
+	return StatusContentTypeUnknown, InvalidStatusContentTypeError{Value: value}
 }
 
 func (s StatusContentType) MarshalJSON() ([]byte, error) {
 	value := s.String()
 	if value == unknownValue {
-		return nil, fmt.Errorf("%q is not a valid status content type", value)
+		return nil, InvalidStatusContentTypeError{Value: value}
 	}
 
-	return json.Marshal(value)
+	data, err := json.Marshal(value)
+	if err != nil {
+		return nil, fmt.Errorf("unable to encode %s to JSON: %w", value, err)
+	}
+
+	return data, nil
+}
+
+type InvalidStatusContentTypeError struct {
+	Value string
+}
+
+func (e InvalidStatusContentTypeError) Error() string {
+	return "'" + e.Value + "' is an invalid status content type: valid values are " +
+		statusContentTypePlainValue + " or " + statusContentTypeTextPlainValue + " for plain text, or " +
+		statusContentTypeMarkdownValue + " or " + statusContentTypeTextMarkdownValue + " for Markdown"
 }
diff --git a/internal/model/status_visibility.go b/internal/model/status_visibility.go
index 84bd76a..48c9262 100644
--- a/internal/model/status_visibility.go
+++ b/internal/model/status_visibility.go
@@ -98,10 +98,10 @@ type InvalidStatusVisibilityError struct {
 }
 
 func (e InvalidStatusVisibilityError) Error() string {
-	return "'" + e.Value + "' is not a valid status visibility value (valid values are " +
+	return "'" + e.Value + "' is not a valid status visibility value: valid values are " +
 		statusVisibilityPublicValue + ", " +
 		statusVisibilityUnlistedValue + ", " +
 		statusVisibilityPrivateValue + ", " +
 		statusVisibilityMutualsOnlyValue + ", " +
-		statusVisibilityDirectValue + ")"
+		statusVisibilityDirectValue
 }