diff --git a/src/main/java/org/elasticsearch/plugin/analysis/ik/AnalysisIkPlugin.java b/src/main/java/org/elasticsearch/plugin/analysis/ik/AnalysisIkPlugin.java
index e6ed25c7..1edad2e3 100644
--- a/src/main/java/org/elasticsearch/plugin/analysis/ik/AnalysisIkPlugin.java
+++ b/src/main/java/org/elasticsearch/plugin/analysis/ik/AnalysisIkPlugin.java
@@ -24,6 +24,9 @@ public Map<String, AnalysisModule.AnalysisProvider<TokenizerFactory>> getTokeniz
 
         extra.put("ik_smart", IkTokenizerFactory::getIkSmartTokenizerFactory);
         extra.put("ik_max_word", IkTokenizerFactory::getIkTokenizerFactory);
+        //For compatibility, otherwise mapping parser will fail during upgrade from 2.x to 5.0
+        //   if you have any field using ik as Analyzer/Tokenizer.
+        extra.put("ik", IkTokenizerFactory::getIkSmartTokenizerFactory);
 
         return extra;
     }
@@ -34,6 +37,9 @@ public Map<String, AnalysisModule.AnalysisProvider<AnalyzerProvider<? extends An
 
         extra.put("ik_smart", IkAnalyzerProvider::getIkSmartAnalyzerProvider);
         extra.put("ik_max_word", IkAnalyzerProvider::getIkAnalyzerProvider);
+        //For compatibility, otherwise mapping parser will fail during upgrade from 2.x to 5.0
+        //   if you have any field using ik as Analyzer/Tokenizer.
+        extra.put("ik", IkAnalyzerProvider::getIkSmartAnalyzerProvider);
 
         return extra;
     }