diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index 25c1efc432..b7ead35a4b 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -46,6 +46,8 @@ The <action> type attribute can be add,update,fix,remove.
     <release version="1.6.0" date="YYYY-MM-DD" description="1.6.0 Release, requires Java 8.">
       <!-- ADD -->
       <action dev="ggregory" type="add" due-to="mufasa1976, Jochen Wiedmann, Gary Gregory">[1.x] Enable multipart/related on FileUpload #314.</action>
+      <!-- FIX -->
+      <action type="fix" dev="ggregory" due-to="Gary Gregory">Replace use of Locale.ENGLISH with Locale.ROOT.</action>
       <!--  UPDATE -->
       <action dev="ggregory" type="update">Bump Java from 6 to 8.</action>
       <action dev="ggregory" type="update">Bump commons-parent from 62 to 70.</action>
diff --git a/src/main/java/org/apache/commons/fileupload/FileUploadBase.java b/src/main/java/org/apache/commons/fileupload/FileUploadBase.java
index 7de61e0408..035480ba58 100644
--- a/src/main/java/org/apache/commons/fileupload/FileUploadBase.java
+++ b/src/main/java/org/apache/commons/fileupload/FileUploadBase.java
@@ -75,7 +75,7 @@ public static final boolean isMultipartContent(final RequestContext ctx) {
         if (contentType == null) {
             return false;
         }
-        return contentType.toLowerCase(Locale.ENGLISH).startsWith(MULTIPART);
+        return contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART);
     }
 
     /**
@@ -489,7 +489,7 @@ protected String getFileName(final FileItemHeaders headers) {
     private String getFileName(final String pContentDisposition) {
         String fileName = null;
         if (pContentDisposition != null) {
-            final String cdl = pContentDisposition.toLowerCase(Locale.ENGLISH);
+            final String cdl = pContentDisposition.toLowerCase(Locale.ROOT);
             if (cdl.startsWith(FORM_DATA) || cdl.startsWith(ATTACHMENT)) {
                 final ParameterParser parser = new ParameterParser();
                 parser.setLowerCaseNames(true);
@@ -532,7 +532,7 @@ protected String getFieldName(final FileItemHeaders headers) {
     private String getFieldName(final String pContentDisposition) {
         String fieldName = null;
         if (pContentDisposition != null
-                && pContentDisposition.toLowerCase(Locale.ENGLISH).startsWith(FORM_DATA)) {
+                && pContentDisposition.toLowerCase(Locale.ROOT).startsWith(FORM_DATA)) {
             final ParameterParser parser = new ParameterParser();
             parser.setLowerCaseNames(true);
             // Parameter parser can handle null input
@@ -718,7 +718,7 @@ private void parseHeaderLine(final FileItemHeadersImpl headers, final String hea
     @Deprecated
     protected final String getHeader(final Map<String, String> headers,
             final String name) {
-        return headers.get(name.toLowerCase(Locale.ENGLISH));
+        return headers.get(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -970,13 +970,13 @@ public void setHeaders(final FileItemHeaders pHeaders) {
 
             final String contentType = ctx.getContentType();
             if (null == contentType
-                    || !contentType.toLowerCase(Locale.ENGLISH).startsWith(MULTIPART)) {
+                    || !contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART)) {
                 throw new InvalidContentTypeException(
                         format("the request neither contains a %s nor a %s nor a %s stream, content type header is %s",
                                MULTIPART_FORM_DATA, MULTIPART_MIXED, MULTIPART_RELATED, contentType));
             }
 
-            multipartRelated = contentType.toLowerCase(Locale.ENGLISH).startsWith(MULTIPART_RELATED);
+            multipartRelated = contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART_RELATED);
 
             @SuppressWarnings("deprecation") // still has to be backward compatible
             final int contentLengthInt = ctx.getContentLength();
@@ -1084,7 +1084,7 @@ private boolean findNextItem() throws IOException {
                     if (fieldName != null) {
                         final String subContentType = headers.getHeader(CONTENT_TYPE);
                         if (subContentType != null
-                                &&  subContentType.toLowerCase(Locale.ENGLISH)
+                                &&  subContentType.toLowerCase(Locale.ROOT)
                                         .startsWith(MULTIPART_MIXED)) {
                             currentFieldName = fieldName;
                             // Multiple files associated with this field name
diff --git a/src/main/java/org/apache/commons/fileupload/ParameterParser.java b/src/main/java/org/apache/commons/fileupload/ParameterParser.java
index 4ce5275a2c..2e93aacb20 100644
--- a/src/main/java/org/apache/commons/fileupload/ParameterParser.java
+++ b/src/main/java/org/apache/commons/fileupload/ParameterParser.java
@@ -329,7 +329,7 @@ public Map<String, String> parse(
             if (paramName != null && !paramName.isEmpty()) {
                 paramName = RFC2231Utility.stripDelimiter(paramName);
                 if (this.lowerCaseNames) {
-                    paramName = paramName.toLowerCase(Locale.ENGLISH);
+                    paramName = paramName.toLowerCase(Locale.ROOT);
                 }
                 params.put(paramName, paramValue);
             }
diff --git a/src/main/java/org/apache/commons/fileupload/util/FileItemHeadersImpl.java b/src/main/java/org/apache/commons/fileupload/util/FileItemHeadersImpl.java
index bf6067f7d1..ad504d043b 100644
--- a/src/main/java/org/apache/commons/fileupload/util/FileItemHeadersImpl.java
+++ b/src/main/java/org/apache/commons/fileupload/util/FileItemHeadersImpl.java
@@ -47,7 +47,7 @@ public class FileItemHeadersImpl implements FileItemHeaders, Serializable {
 
     @Override
     public String getHeader(final String name) {
-        final String nameLower = name.toLowerCase(Locale.ENGLISH);
+        final String nameLower = name.toLowerCase(Locale.ROOT);
         final List<String> headerValueList = headerNameToValueListMap.get(nameLower);
         if (null == headerValueList) {
             return null;
@@ -62,7 +62,7 @@ public Iterator<String> getHeaderNames() {
 
     @Override
     public Iterator<String> getHeaders(final String name) {
-        final String nameLower = name.toLowerCase(Locale.ENGLISH);
+        final String nameLower = name.toLowerCase(Locale.ROOT);
         List<String> headerValueList = headerNameToValueListMap.get(nameLower);
         if (null == headerValueList) {
             headerValueList = Collections.emptyList();
@@ -77,7 +77,7 @@ public Iterator<String> getHeaders(final String name) {
      * @param value value of this header
      */
     public synchronized void addHeader(final String name, final String value) {
-        final String nameLower = name.toLowerCase(Locale.ENGLISH);
+        final String nameLower = name.toLowerCase(Locale.ROOT);
         List<String> headerValueList = headerNameToValueListMap.get(nameLower);
         if (null == headerValueList) {
             headerValueList = new ArrayList<>();
diff --git a/src/main/java/org/apache/commons/fileupload/util/mime/MimeUtility.java b/src/main/java/org/apache/commons/fileupload/util/mime/MimeUtility.java
index d0378a3537..a4edb5c345 100644
--- a/src/main/java/org/apache/commons/fileupload/util/mime/MimeUtility.java
+++ b/src/main/java/org/apache/commons/fileupload/util/mime/MimeUtility.java
@@ -210,7 +210,7 @@ private static String decodeWord(final String word) throws ParseException, Unsup
         }
 
         // pull out the character set information (this is the MIME name at this point).
-        final String charset = word.substring(2, charsetPos).toLowerCase(Locale.ENGLISH);
+        final String charset = word.substring(2, charsetPos).toLowerCase(Locale.ROOT);
 
         // now pull out the encoding token the same way.
         final int encodingPos = word.indexOf('?', charsetPos + 1);
@@ -269,7 +269,7 @@ private static String javaCharset(final String charset) {
             return null;
         }
 
-        final String mappedCharset = MIME2JAVA.get(charset.toLowerCase(Locale.ENGLISH));
+        final String mappedCharset = MIME2JAVA.get(charset.toLowerCase(Locale.ROOT));
         // if there is no mapping, then the original name is used.  Many of the MIME character set
         // names map directly back into Java.  The reverse isn't necessarily true.
         if (mappedCharset == null) {