diff --git a/src/main/java/org/apache/commons/lang3/LocaleUtils.java b/src/main/java/org/apache/commons/lang3/LocaleUtils.java
index 39b81a49042..176a4372710 100644
--- a/src/main/java/org/apache/commons/lang3/LocaleUtils.java
+++ b/src/main/java/org/apache/commons/lang3/LocaleUtils.java
@@ -255,16 +255,17 @@ public static List<Locale> localeLookupList(final Locale locale, final Locale de
      * </p>
      *
      * @param str the String to parse as a Locale.
+     * @param supportDash support strings with '-'.
      * @return a Locale parsed from the given String.
      * @throws IllegalArgumentException if the given String can not be parsed.
      * @see Locale
      */
-    private static Locale parseLocale(final String str) {
+    private static Locale parseLocale(final String str, final boolean supportDash) {
         if (isISO639LanguageCode(str)) {
             return new Locale(str);
         }
         final int limit = 3;
-        final char separator = str.indexOf(UNDERSCORE) != -1 ? UNDERSCORE : DASH;
+        final char separator = (!supportDash || str.indexOf(UNDERSCORE) != -1) ? UNDERSCORE : DASH;
         final String[] segments = str.split(String.valueOf(separator), 3);
         final String language = segments[0];
         if (segments.length == 2) {
@@ -305,7 +306,6 @@ public static Locale toLocale(final Locale locale) {
      *   LocaleUtils.toLocale("")           = new Locale("", "")
      *   LocaleUtils.toLocale("en")         = new Locale("en", "")
      *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
-     *   LocaleUtils.toLocale("en-GB")      = new Locale("en", "GB")
      *   LocaleUtils.toLocale("en_001")     = new Locale("en", "001")
      *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
      * </pre>
@@ -317,16 +317,58 @@ public static Locale toLocale(final Locale locale) {
      * <p>This method validates the input strictly.
      * The language code must be lowercase.
      * The country code must be uppercase.
-     * The separator must be an underscore or a dash.
+     * The separator must be an underscore.
      * The length must be correct.
      * </p>
      *
      * @param str  the locale String to convert, null returns null
      * @return a Locale, null if null input
      * @throws IllegalArgumentException if the string is an invalid format
-     * @see Locale#forLanguageTag(String)
+     * @see Locale
      */
     public static Locale toLocale(final String str) {
+        return toLocale(str, false);
+    }
+
+    /**
+     * Converts a String to a Locale.
+     *
+     * <p>This method takes a string format of a locale or language tag
+     * if supportDash is true and creates the locale object from it.</p>
+     *
+     * <pre>
+     *   LocaleUtils.toLocale("", false)          = new Locale("", "")
+     *   LocaleUtils.toLocale("", true)           = new Locale("", "")
+     *   LocaleUtils.toLocale("en", false)        = new Locale("en", "")
+     *   LocaleUtils.toLocale("en", true)         = new Locale("en", "")
+     *   LocaleUtils.toLocale("en_GB", false)     = new Locale("en", "GB")
+     *   LocaleUtils.toLocale("en_GB", true)      = new Locale("en", "GB")
+     *   LocaleUtils.toLocale("en-GB", false)     = throws IllegalArgumentException()
+     *   LocaleUtils.toLocale("en-GB", true)      = new Locale("en", "GB")
+     *   LocaleUtils.toLocale("en_001", false)    = new Locale("en", "001")
+     *   LocaleUtils.toLocale("en_001", true)     = new Locale("en", "001")
+     *   LocaleUtils.toLocale("en_GB_xxx", false) = new Locale("en", "GB", "xxx")   (#)
+     *   LocaleUtils.toLocale("en_GB_xxx", true)  = new Locale("en", "GB", "xxx")   (#)
+     * </pre>
+     *
+     * <p>(#) The behavior of the JDK variant constructor changed between JDK1.3 and JDK1.4.
+     * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
+     * Thus, the result from getVariant() may vary depending on your JDK.</p>
+     *
+     * <p>This method validates the input strictly.
+     * The language code must be lowercase.
+     * The country code must be uppercase.
+     * The separator must be an underscore.
+     * The length must be correct.
+     * </p>
+     *
+     * @param str  the locale String to convert, null returns null
+     * @param supportDash support strings with '-'.
+     * @return a Locale, null if null input
+     * @throws IllegalArgumentException if the string is an invalid format
+     * @see Locale
+     */
+    protected static Locale toLocale(final String str, final boolean supportDash) {
         if (str == null) {
             // TODO Should this return the default locale?
             return null;
@@ -342,7 +384,7 @@ public static Locale toLocale(final String str) {
             throw new IllegalArgumentException("Invalid locale format: " + str);
         }
         final char ch0 = str.charAt(0);
-        if (ch0 == UNDERSCORE || ch0 == DASH) {
+        if (ch0 == UNDERSCORE || (supportDash && ch0 == DASH)) {
             if (len < 3) {
                 throw new IllegalArgumentException("Invalid locale format: " + str);
             }
@@ -363,7 +405,7 @@ public static Locale toLocale(final String str) {
             return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4));
         }
 
-        return parseLocale(str);
+        return parseLocale(str, supportDash);
     }
 
     /**
diff --git a/src/test/java/org/apache/commons/lang3/LocaleUtilsTest.java b/src/test/java/org/apache/commons/lang3/LocaleUtilsTest.java
index dc9e3969d0b..0b82ac62297 100644
--- a/src/test/java/org/apache/commons/lang3/LocaleUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/LocaleUtilsTest.java
@@ -157,7 +157,7 @@ private static void assertValidToLocale(final String language) {
     }
 
     /**
-     * Pass in a valid language, test toLocale.
+     * Pass in a valid locale, test toLocale.
      *
      * @param localeString to pass to toLocale()
      * @param language of the resulting Locale
@@ -173,7 +173,23 @@ private static void assertValidToLocale(final String localeString, final String
     }
 
     /**
-     * Pass in a valid language, test toLocale.
+     * Pass in a valid language tag, test toLocale.
+     *
+     * @param localeString to pass to toLocale()
+     * @param language of the resulting Locale
+     * @param country of the resulting Locale
+     */
+    private static void assertValidToLocaleIncludingDash(final String localeString, final String language, final String country) {
+        final Locale locale = LocaleUtils.toLocale(localeString, true);
+        assertNotNull(locale, "valid locale");
+        assertEquals(language, locale.getLanguage());
+        assertEquals(country, locale.getCountry());
+        //variant is empty
+        assertTrue(StringUtils.isEmpty(locale.getVariant()));
+    }
+
+    /**
+     * Pass in a valid locale, test toLocale.
      *
      * @param localeString to pass to toLocale()
      * @param language of the resulting Locale
@@ -190,6 +206,23 @@ private static void assertValidToLocale(
         assertEquals(variant, locale.getVariant());
     }
 
+    /**
+     * Pass in a valid language tag, test toLocale.
+     *
+     * @param localeString to pass to toLocale()
+     * @param language of the resulting Locale
+     * @param country of the resulting Locale
+     * @param variant of the resulting Locale
+     */
+    private static void assertValidToLocaleIncludingDash(
+            final String localeString, final String language,
+            final String country, final String variant) {
+        final Locale locale = LocaleUtils.toLocale(localeString, true);
+        assertNotNull(locale, "valid locale");
+        assertEquals(language, locale.getLanguage());
+        assertEquals(country, locale.getCountry());
+        assertEquals(variant, locale.getVariant());
+    }
     @BeforeEach
     public void setUp() {
         // Testing #LANG-304. Must be called before availableLocaleSet is called.
@@ -496,10 +529,14 @@ public void testToLocale_1Part() {
     @Test
     public void testToLocale_2Part() {
         assertValidToLocale("us_EN", "us", "EN");
-        assertValidToLocale("us-EN", "us", "EN");
+        assertValidToLocaleIncludingDash("us-EN", "us", "EN");
         //valid though doesn't exist
         assertValidToLocale("us_ZH", "us", "ZH");
 
+        assertThrows(
+                IllegalArgumentException.class,
+                () -> LocaleUtils.toLocale("us-EN"),
+                "Should fail dash not supported");
         assertThrows(
                 IllegalArgumentException.class,
                 () -> LocaleUtils.toLocale("us_En"),
@@ -528,7 +565,7 @@ public void testToLocale_2Part() {
     @Test
     public void testToLocale_3Part() {
         assertValidToLocale("us_EN_A", "us", "EN", "A");
-        assertValidToLocale("us-EN-A", "us", "EN", "A");
+        assertValidToLocaleIncludingDash("us-EN-A", "us", "EN", "A");
         // this isn't pretty, but was caused by a jdk bug it seems
         // https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4210525
         if (SystemUtils.isJavaVersionAtLeast(JAVA_1_4)) {
@@ -538,6 +575,7 @@ public void testToLocale_3Part() {
             assertValidToLocale("us_EN_a", "us", "EN", "A");
             assertValidToLocale("us_EN_SFsafdFDsdfF", "us", "EN", "SFSAFDFDSDFF");
         }
+        assertThrows(IllegalArgumentException.class, () -> LocaleUtils.toLocale("us-EN-A"), "Should fail as dash is not supported");
         assertThrows(IllegalArgumentException.class, () -> LocaleUtils.toLocale("us_EN-a"), "Should fail as no consistent delimiter");
         assertThrows(IllegalArgumentException.class, () -> LocaleUtils.toLocale("uu_UU_"), "Must be 3, 5 or 7+ in length");
         // LANG-1741