diff --git a/src/main/java/org/apache/ibatis/session/Configuration.java b/src/main/java/org/apache/ibatis/session/Configuration.java
index dfc8dd0218c..8234250a6ed 100644
--- a/src/main/java/org/apache/ibatis/session/Configuration.java
+++ b/src/main/java/org/apache/ibatis/session/Configuration.java
@@ -1,5 +1,5 @@
 /*
- *    Copyright 2009-2024 the original author or authors.
+ *    Copyright 2009-2025 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -15,20 +15,6 @@
  */
 package org.apache.ibatis.session;
 
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-import java.util.Properties;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.locks.ReentrantLock;
-import java.util.function.BiFunction;
-
 import org.apache.ibatis.binding.MapperRegistry;
 import org.apache.ibatis.builder.CacheRefResolver;
 import org.apache.ibatis.builder.IncompleteElementException;
@@ -97,6 +83,20 @@
 import org.apache.ibatis.type.TypeHandler;
 import org.apache.ibatis.type.TypeHandlerRegistry;
 
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Properties;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.BiFunction;
+
 /**
  * @author Clinton Begin
  */
@@ -1113,6 +1113,7 @@ protected static class StrictMap<V> extends ConcurrentHashMap<String, V> {
     private static final long serialVersionUID = -4950446264854982944L;
     private final String name;
     private BiFunction<V, V, String> conflictMessageProducer;
+    private static final Object AMBIGUITY_INSTANCE = new Object();
 
     public StrictMap(String name, int initialCapacity, float loadFactor) {
       super(initialCapacity, loadFactor);
@@ -1162,7 +1163,7 @@ public V put(String key, V value) {
         if (super.get(shortKey) == null) {
           super.put(shortKey, value);
         } else {
-          super.put(shortKey, (V) new Ambiguity(shortKey));
+          super.put(shortKey, (V) AMBIGUITY_INSTANCE);
         }
       }
       return super.put(key, value);
@@ -1183,25 +1184,13 @@ public V get(Object key) {
       if (value == null) {
         throw new IllegalArgumentException(name + " does not contain value for " + key);
       }
-      if (value instanceof Ambiguity) {
-        throw new IllegalArgumentException(((Ambiguity) value).getSubject() + " is ambiguous in " + name
+      if (AMBIGUITY_INSTANCE == value) {
+        throw new IllegalArgumentException(key + " is ambiguous in " + name
             + " (try using the full name including the namespace, or rename one of the entries)");
       }
       return value;
     }
 
-    protected static class Ambiguity {
-      private final String subject;
-
-      public Ambiguity(String subject) {
-        this.subject = subject;
-      }
-
-      public String getSubject() {
-        return subject;
-      }
-    }
-
     private String getShortName(String key) {
       final String[] keyParts = key.split("\\.");
       return keyParts[keyParts.length - 1];
diff --git a/src/test/java/org/apache/ibatis/submitted/global_variables_defaults/ConfigurationTest.java b/src/test/java/org/apache/ibatis/submitted/global_variables_defaults/ConfigurationTest.java
index 6f940466f5d..1550979147c 100644
--- a/src/test/java/org/apache/ibatis/submitted/global_variables_defaults/ConfigurationTest.java
+++ b/src/test/java/org/apache/ibatis/submitted/global_variables_defaults/ConfigurationTest.java
@@ -1,5 +1,5 @@
 /*
- *    Copyright 2009-2023 the original author or authors.
+ *    Copyright 2009-2025 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -15,12 +15,11 @@
  */
 package org.apache.ibatis.submitted.global_variables_defaults;
 
-import java.io.IOException;
-import java.io.Reader;
-import java.util.Properties;
-
+import org.apache.ibatis.builder.StaticSqlSource;
 import org.apache.ibatis.datasource.unpooled.UnpooledDataSource;
 import org.apache.ibatis.io.Resources;
+import org.apache.ibatis.mapping.MappedStatement;
+import org.apache.ibatis.mapping.SqlCommandType;
 import org.apache.ibatis.parsing.PropertyParser;
 import org.apache.ibatis.session.Configuration;
 import org.apache.ibatis.session.SqlSessionFactory;
@@ -29,6 +28,10 @@
 import org.assertj.core.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.io.IOException;
+import java.io.Reader;
+import java.util.Properties;
+
 class ConfigurationTest {
 
   @Test
@@ -79,4 +82,27 @@ void applyPropertyValueOnXmlConfiguration() throws IOException {
 
   }
 
+  @Test
+  void testAmbiguityCache() {
+    Configuration configuration = new Configuration();
+
+    configuration.addMappedStatement(
+        new MappedStatement.Builder(configuration, "org.apache.ibatis.submitted.DemoMapper1.selectById",
+            new StaticSqlSource(configuration, "select * from test where id = 1"), SqlCommandType.SELECT).build());
+    configuration
+        .addMappedStatement(new MappedStatement.Builder(configuration, "org.apache.ibatis.submitted.DemoMapper1.test",
+            new StaticSqlSource(configuration, "select * from test"), SqlCommandType.SELECT).build());
+    configuration
+        .addMappedStatement(new MappedStatement.Builder(configuration, "org.apache.ibatis.submitted.DemoMapper2.test",
+            new StaticSqlSource(configuration, "select * from test"), SqlCommandType.SELECT).build());
+
+    Assertions.assertThat(configuration.getMappedStatement("selectById")).isNotNull();
+    Assertions.assertThat(configuration.getMappedStatement("org.apache.ibatis.submitted.DemoMapper1.test")).isNotNull();
+    Assertions.assertThat(configuration.getMappedStatement("org.apache.ibatis.submitted.DemoMapper2.test")).isNotNull();
+
+    Assertions.assertThatThrownBy(() -> configuration.getMappedStatement("test"))
+        .isInstanceOf(IllegalArgumentException.class).hasMessage(
+            "test is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)");
+  }
+
 }