diff --git a/openapi3/schema.go b/openapi3/schema.go
index acf88f191..986c8337e 100644
--- a/openapi3/schema.go
+++ b/openapi3/schema.go
@@ -841,14 +841,14 @@ func (schema *Schema) visitSetOperations(settings *schemaValidationSettings, val
 
 		if schema.Discriminator != nil {
 			/* Find mapped object by ref */
-			if valuemap, okcheck := value.(map[string]interface{}); okcheck {
+			if valuemap, okcheck := value.(map[string]string); okcheck {
 				pn := schema.Discriminator.PropertyName
 				if discriminatorVal, okcheck := valuemap[pn]; okcheck {
 					if len(schema.Discriminator.Mapping) > 0 {
-						if mapref, okcheck := schema.Discriminator.Mapping[discriminatorVal.(string)]; okcheck {
-							for _, item := range v {
-								if item.Ref == mapref {
-									return item.Value.visitJSON(settings, value)
+						if mapref, okcheck := schema.Discriminator.Mapping[discriminatorVal]; okcheck {
+							for _, oneof := range v {
+								if oneof.Ref == mapref {
+									return oneof.Value.visitJSON(settings, value)
 								}
 							}
 						}
@@ -857,9 +857,9 @@ func (schema *Schema) visitSetOperations(settings *schemaValidationSettings, val
 						``It is implied, that the property to which discriminator refers, contains the
 						name of the target schema. In the example above, the objectType property should
 						contain either simpleObject, or complexObject string.''*/
-						for _, oneof := range schema.OneOf {
-							if strings.HasSuffix(oneof.Ref, discriminatorVal.(string)) {
-								return oneof.Value.visitJSON(settings, value)
+						for _, v := range schema.OneOf {
+							if strings.HasSuffix(v.Ref, discriminatorVal) {
+								return v.Value.visitJSON(settings, value)
 							}
 						}
 					}