diff --git a/topic/src/main/java/tech/ydb/topic/description/CodecRegistry.java b/topic/src/main/java/tech/ydb/topic/description/CodecRegistry.java
index 513201770..04df98b78 100644
--- a/topic/src/main/java/tech/ydb/topic/description/CodecRegistry.java
+++ b/topic/src/main/java/tech/ydb/topic/description/CodecRegistry.java
@@ -1,7 +1,7 @@
 package tech.ydb.topic.description;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -17,10 +17,11 @@ public class CodecRegistry {
 
     private static final Logger logger = LoggerFactory.getLogger(CodecRegistry.class);
 
-    final Map<Integer, Codec> customCodecMap;
+    // registerCodec may be called at any moment, while getCodec is used by the compression and the
+    // decompression threads of every reader and writer created from the same TopicClient
+    private final Map<Integer, Codec> customCodecMap = new ConcurrentHashMap<>();
 
     public CodecRegistry() {
-        customCodecMap = new HashMap<>();
         for (Codec codec: StandardCodecs.getAvailableCodecs()) {
             customCodecMap.put(codec.getId(), codec);
         }
@@ -32,11 +33,12 @@ public CodecRegistry() {
      * @return previous implementation with associated codec
      */
     public Codec registerCodec(Codec codec) {
-        assert codec != null;
+        if (codec == null) {
+            throw new IllegalArgumentException("Codec must be not null");
+        }
         int codecId = codec.getId();
 
         Codec result = customCodecMap.put(codecId, codec);
-
         if (result != null) {
             logger.info(
                     "Replace codec which have already associated with this id. CodecId: {} Codec: {}",
diff --git a/topic/src/test/java/tech/ydb/topic/impl/CodecRegistryTest.java b/topic/src/test/java/tech/ydb/topic/impl/CodecRegistryTest.java
index 35e0baa77..b341c1093 100644
--- a/topic/src/test/java/tech/ydb/topic/impl/CodecRegistryTest.java
+++ b/topic/src/test/java/tech/ydb/topic/impl/CodecRegistryTest.java
@@ -1,5 +1,9 @@
 package tech.ydb.topic.impl;
 
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
@@ -7,10 +11,6 @@
 import tech.ydb.topic.description.Codec;
 import tech.ydb.topic.description.CodecRegistry;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-
 /**
  * Unit tests for check simple logic for register custom codec
  *
@@ -19,7 +19,7 @@
 public class CodecRegistryTest {
     CodecRegistry registry;
 
-    private static final int codecId = 10113;
+    private static final int CUSTOM_ID = 10113;
 
     @Before
     public void beforeTest() {
@@ -34,15 +34,14 @@ public void registerCustomCodecShouldDoubleRegisterCodecAndReturnLastCodec() {
         registry.registerCodec(codec1);
         Assert.assertEquals(codec1, registry.registerCodec(codec2));
 
-        Assert.assertEquals(codec2, registry.getCodec(codecId));
-        Assert.assertNotEquals(codec1, registry.getCodec(codecId));
+        Assert.assertEquals(codec2, registry.getCodec(CUSTOM_ID));
+        Assert.assertNotEquals(codec1, registry.getCodec(CUSTOM_ID));
     }
 
     @Test
     public void registerCustomCodecShouldNotAcceptNull() {
-        Assert.assertThrows(
-                AssertionError.class,
-                () -> registry.registerCodec(null));
+        Exception ex = Assert.assertThrows(IllegalArgumentException.class, () -> registry.registerCodec(null));
+        Assert.assertEquals("Codec must be not null", ex.getMessage());
     }
 
     @Test
@@ -65,7 +64,12 @@ static class CodecTopic implements Codec {
         int codec;
 
         public CodecTopic() {
-            this.codec = codecId;
+            this.codec = CUSTOM_ID;
+        }
+
+        @Override
+        public String toString() {
+            return "CustomCodec";
         }
 
         public void setCodecId(int codecId) {