diff --git a/src/main/java/io/vertx/core/impl/SysProps.java b/src/main/java/io/vertx/core/impl/SysProps.java
index fca0332af28..0c62af11d1c 100644
--- a/src/main/java/io/vertx/core/impl/SysProps.java
+++ b/src/main/java/io/vertx/core/impl/SysProps.java
@@ -4,11 +4,6 @@
 
 public enum SysProps {
 
-  /**
-   * Defines a mode for base64 JSON conversions that is compatible with Vert.x 3
-   */
-  JSON_BASE_64("vertx.json.base64"),
-
   /**
    * Cluster manager to use class FQN.
    *
diff --git a/src/main/java/io/vertx/core/json/impl/JsonUtil.java b/src/main/java/io/vertx/core/json/impl/JsonUtil.java
index 124a5683a39..19d6048c652 100644
--- a/src/main/java/io/vertx/core/json/impl/JsonUtil.java
+++ b/src/main/java/io/vertx/core/json/impl/JsonUtil.java
@@ -11,7 +11,6 @@
 package io.vertx.core.json.impl;
 
 import io.vertx.core.buffer.Buffer;
-import io.vertx.core.impl.SysProps;
 import io.vertx.core.json.JsonArray;
 import io.vertx.core.json.JsonObject;
 import io.vertx.core.shareddata.Shareable;
@@ -32,23 +31,8 @@
  */
 public final class JsonUtil {
 
-  public static final Base64.Encoder BASE64_ENCODER;
-  public static final Base64.Decoder BASE64_DECODER;
-
-  static {
-    /*
-     * Vert.x 3.x Json supports RFC-7493, however the JSON encoder/decoder format was incorrect.
-     * Users who might need to interop with Vert.x 3.x applications should set the system property
-     * {@code vertx.json.base64} to {@code legacy}.
-     */
-    if ("legacy".equalsIgnoreCase(SysProps.JSON_BASE_64.get())) {
-      BASE64_ENCODER = Base64.getEncoder();
-      BASE64_DECODER = Base64.getDecoder();
-    } else {
-      BASE64_ENCODER = Base64.getUrlEncoder().withoutPadding();
-      BASE64_DECODER = Base64.getUrlDecoder();
-    }
-  }
+  public static final Base64.Encoder BASE64_ENCODER = Base64.getUrlEncoder().withoutPadding();
+  public static final Base64.Decoder BASE64_DECODER = Base64.getUrlDecoder();
 
   /**
    * Wraps well known java types to adhere to the Json expected types.