diff --git a/openapi2/marsh.go b/openapi2/marsh.go
index b15f3b82c..5aa162a72 100644
--- a/openapi2/marsh.go
+++ b/openapi2/marsh.go
@@ -17,10 +17,18 @@ func unmarshalError(jsonUnmarshalErr error) error {
 }
 
 func unmarshal(data []byte, v interface{}) error {
+	var jsonErr, yamlErr error
+
 	// See https://github.com/getkin/kin-openapi/issues/680
-	if err := json.Unmarshal(data, v); err != nil {
-		// UnmarshalStrict(data, v) TODO: investigate how ymlv3 handles duplicate map keys
-		return yaml.Unmarshal(data, v)
+	if jsonErr = json.Unmarshal(data, v); jsonErr == nil {
+		return nil
+	}
+
+	// UnmarshalStrict(data, v) TODO: investigate how ymlv3 handles duplicate map keys
+	if yamlErr = yaml.Unmarshal(data, v); yamlErr == nil {
+		return nil
 	}
-	return nil
+
+	// If both unmarshaling attempts fail, return a new error that includes both errors
+	return fmt.Errorf("failed to unmarshal data: json error: %v, yaml error: %v", jsonErr, yamlErr)
 }
diff --git a/openapi3/marsh.go b/openapi3/marsh.go
index 18036ae78..9be7bb44c 100644
--- a/openapi3/marsh.go
+++ b/openapi3/marsh.go
@@ -17,10 +17,18 @@ func unmarshalError(jsonUnmarshalErr error) error {
 }
 
 func unmarshal(data []byte, v interface{}) error {
+	var jsonErr, yamlErr error
+
 	// See https://github.com/getkin/kin-openapi/issues/680
-	if err := json.Unmarshal(data, v); err != nil {
-		// UnmarshalStrict(data, v) TODO: investigate how ymlv3 handles duplicate map keys
-		return yaml.Unmarshal(data, v)
+	if jsonErr = json.Unmarshal(data, v); jsonErr == nil {
+		return nil
+	}
+
+	// UnmarshalStrict(data, v) TODO: investigate how ymlv3 handles duplicate map keys
+	if yamlErr = yaml.Unmarshal(data, v); yamlErr == nil {
+		return nil
 	}
-	return nil
+
+	// If both unmarshaling attempts fail, return a new error that includes both errors
+	return fmt.Errorf("failed to unmarshal data: json error: %v, yaml error: %v", jsonErr, yamlErr)
 }