diff --git a/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/InstrumentedType.java b/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/InstrumentedType.java
index 1df77cc700..77c0c47005 100644
--- a/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/InstrumentedType.java
+++ b/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/InstrumentedType.java
@@ -1842,13 +1842,16 @@ private static boolean isValidIdentifier(String[] identifier) {
          * @return {@code true} if the given identifier is valid.
          */
         private static boolean isValidIdentifier(String identifier) {
-            if (KEYWORDS.contains(identifier) || identifier.length() == 0 || !Character.isUnicodeIdentifierStart(identifier.charAt(0))) {
+            if (KEYWORDS.contains(identifier)
+                    || identifier.length() == 0
+                    || !(Character.isJavaIdentifierStart(identifier.charAt(0))
+                    || Character.isUnicodeIdentifierStart(identifier.charAt(0)))) {
                 return false;
             } else if (identifier.equals(PackageDescription.PACKAGE_CLASS_NAME)) {
                 return true;
             }
             for (int index = 1; index < identifier.length(); index++) {
-                if (!Character.isUnicodeIdentifierPart(identifier.charAt(index))) {
+                if (!(Character.isJavaIdentifierPart(identifier.charAt(index)) || Character.isUnicodeIdentifierPart(identifier.charAt(index)))) {
                     return false;
                 }
             }
diff --git a/pom.xml b/pom.xml
index cb8bb8c53c..632ac70ad0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -988,7 +988,7 @@
             <id>surefire-enable-dynamic-attach</id>
             <activation>
                 <activeByDefault>false</activeByDefault>
-                <jdk>[22,)</jdk>
+                <jdk>[21,)</jdk>
             </activation>
             <properties>
                 <surefire.arguments>-XX:+EnableDynamicAgentLoading</surefire.arguments>