diff --git a/spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/ClassFileTransformerAdapter.java b/spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/ClassFileTransformerAdapter.java
index 46b56d5364d..3f95f2d4681 100644
--- a/spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/ClassFileTransformerAdapter.java
+++ b/spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/ClassFileTransformerAdapter.java
@@ -57,42 +57,40 @@ class ClassFileTransformerAdapter implements ClassFileTransformer {
 			ClassLoader loader, String className, Class<?> classBeingRedefined,
 			ProtectionDomain protectionDomain, byte[] classfileBuffer) {
 
-		synchronized (this) {
-			if (this.currentlyTransforming.get() == Boolean.TRUE) {
-				// Defensively back out when called from within the transform delegate below:
-				// in particular, for the over-eager transformer implementation in Hibernate.
-				return null;
-			}
+		if (this.currentlyTransforming.get() == Boolean.TRUE) {
+			// Defensively back out when called from within the transform delegate below:
+			// in particular, for the over-eager transformer implementation in Hibernate.
+			return null;
+		}
 
-			this.currentlyTransforming.set(Boolean.TRUE);
-			try {
-				byte[] transformed = this.classTransformer.transform(
-						loader, className, classBeingRedefined, protectionDomain, classfileBuffer);
-				if (transformed != null && logger.isDebugEnabled()) {
-					logger.debug("Transformer of class [" + this.classTransformer.getClass().getName() +
-							"] transformed class [" + className + "]; bytes in=" +
-							classfileBuffer.length + "; bytes out=" + transformed.length);
-				}
-				return transformed;
+		this.currentlyTransforming.set(Boolean.TRUE);
+		try {
+			byte[] transformed = this.classTransformer.transform(
+					loader, className, classBeingRedefined, protectionDomain, classfileBuffer);
+			if (transformed != null && logger.isDebugEnabled()) {
+				logger.debug("Transformer of class [" + this.classTransformer.getClass().getName() +
+						"] transformed class [" + className + "]; bytes in=" +
+						classfileBuffer.length + "; bytes out=" + transformed.length);
 			}
-			catch (ClassCircularityError ex) {
-				if (logger.isErrorEnabled()) {
-					logger.error("Circularity error while weaving class [" + className + "] with " +
-							"transformer of class [" + this.classTransformer.getClass().getName() + "]", ex);
-				}
-				throw new IllegalStateException("Failed to weave class [" + className + "]", ex);
+			return transformed;
+		}
+		catch (ClassCircularityError ex) {
+			if (logger.isErrorEnabled()) {
+				logger.error("Circularity error while weaving class [" + className + "] with " +
+						"transformer of class [" + this.classTransformer.getClass().getName() + "]", ex);
 			}
-			catch (Throwable ex) {
-				if (logger.isWarnEnabled()) {
-					logger.warn("Error weaving class [" + className + "] with transformer of class [" +
-							this.classTransformer.getClass().getName() + "]", ex);
-				}
-				// The exception will be ignored by the class loader, anyway...
-				throw new IllegalStateException("Could not weave class [" + className + "]", ex);
-			}
-			finally {
-				this.currentlyTransforming.remove();
+			throw new IllegalStateException("Failed to weave class [" + className + "]", ex);
+		}
+		catch (Throwable ex) {
+			if (logger.isWarnEnabled()) {
+				logger.warn("Error weaving class [" + className + "] with transformer of class [" +
+						this.classTransformer.getClass().getName() + "]", ex);
 			}
+			// The exception will be ignored by the class loader, anyway...
+			throw new IllegalStateException("Could not weave class [" + className + "]", ex);
+		}
+		finally {
+			this.currentlyTransforming.remove();
 		}
 	}