diff --git a/src/main/java/org/apache/commons/math3/exception/util/ExceptionContext.java b/src/main/java/org/apache/commons/math3/exception/util/ExceptionContext.java
index a9fd95cec..1a78bd38f 100644
--- a/src/main/java/org/apache/commons/math3/exception/util/ExceptionContext.java
+++ b/src/main/java/org/apache/commons/math3/exception/util/ExceptionContext.java
@@ -283,12 +283,12 @@ public class ExceptionContext implements Serializable {
     private void serializeContext(ObjectOutputStream out)
         throws IOException {
         // Step 1.
-        final int len = context.keySet().size();
+        final int len = context.size();
         out.writeInt(len);
-        for (String key : context.keySet()) {
+        for (Map.Entry<String, Object> entry : context.entrySet()) {
             // Step 2.
-            out.writeObject(key);
-            final Object value = context.get(key);
+            out.writeObject(entry.getKey());
+            final Object value = entry.getValue();
             if (value instanceof Serializable) {
                 // Step 3a.
                 out.writeObject(value);