diff --git a/modules/swagger-parser/src/main/java/io/swagger/parser/util/RefUtils.java b/modules/swagger-parser/src/main/java/io/swagger/parser/util/RefUtils.java
index 42f9dd0128..a3122f3c1e 100644
--- a/modules/swagger-parser/src/main/java/io/swagger/parser/util/RefUtils.java
+++ b/modules/swagger-parser/src/main/java/io/swagger/parser/util/RefUtils.java
@@ -2,11 +2,13 @@
 
 import io.swagger.models.auth.AuthorizationValue;
 import io.swagger.models.refs.RefFormat;
+import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.lang3.StringUtils;
 
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.InputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.file.FileSystem;
@@ -138,7 +140,9 @@ public static String readExternalRef(String file, RefFormat refFormat, List<Auth
                 final Path pathToUse = parentDirectory.resolve(file).normalize();
 
                 if(Files.exists(pathToUse)) {
-                    result = IOUtils.toString(new FileInputStream(pathToUse.toFile()), "UTF-8");
+                    try(InputStream inputStream = new FileInputStream(pathToUse.toFile())){
+                        result = IOUtils.toString(inputStream, "UTF-8");
+                    }
                 } else {
                     String url = file;
                     if(url.contains("..")) {
@@ -149,7 +153,9 @@ public static String readExternalRef(String file, RefFormat refFormat, List<Auth
                     final Path pathToUse2 = parentDirectory.resolve(url).normalize();
 
                     if(Files.exists(pathToUse2)) {
-                        result = IOUtils.toString(new FileInputStream(pathToUse2.toFile()), "UTF-8");
+                        try(InputStream inputStream = new FileInputStream(pathToUse2.toFile())){
+                            result = IOUtils.toString(inputStream, "UTF-8");
+                        }
                     }
                 }
                 if (result == null){