diff --git a/src/main/java/org/mvel2/MVELRuntime.java b/src/main/java/org/mvel2/MVELRuntime.java
index 43d7eed4c..05a6d305c 100644
--- a/src/main/java/org/mvel2/MVELRuntime.java
+++ b/src/main/java/org/mvel2/MVELRuntime.java
@@ -24,6 +24,7 @@
 import org.mvel2.debug.Debugger;
 import org.mvel2.debug.DebuggerContext;
 import org.mvel2.integration.VariableResolverFactory;
+import org.mvel2.optimizers.OptimizerFactory;
 import org.mvel2.util.ErrorUtil;
 import org.mvel2.util.ExecutionStack;
 
@@ -164,6 +165,9 @@ else if (stk.isEmpty()) {
         throw e;
       }
     }
+    finally {
+      OptimizerFactory.clearThreadAccessorOptimizer();
+    }
   }
 
   /**
diff --git a/src/main/java/org/mvel2/optimizers/OptimizerFactory.java b/src/main/java/org/mvel2/optimizers/OptimizerFactory.java
index d71fe372f..1604f34b9 100644
--- a/src/main/java/org/mvel2/optimizers/OptimizerFactory.java
+++ b/src/main/java/org/mvel2/optimizers/OptimizerFactory.java
@@ -101,7 +101,9 @@ public static void setDefaultOptimizer(String name) {
       //noinspection unchecked
       AccessorOptimizer ao = accessorCompilers.get(defaultOptimizer = name);
       ao.init();
-      setThreadAccessorOptimizer(ao.getClass());
+      //clear optimizer so next call to getThreadAccessorOptimizer uses the default again, don't set thread optimizer
+      //or else static initializers setting the default will unintentionally set up ThreadLocals
+      threadOptimizer.set(null);
     }
     catch (Exception e) {
       throw new RuntimeException("unable to instantiate accessor compiler", e);