diff --git a/gherkin/config.feature b/gherkin/config.feature
index 227e4b6..b54b5da 100644
--- a/gherkin/config.feature
+++ b/gherkin/config.feature
@@ -5,7 +5,7 @@ Feature: Configuration Test
   | --------------------- | ------------------------------ | ------------------------------------------------------------------------------- | ---------------------------- | ----------------------------- | ------------------- |
   | resolver              | FLAGD_RESOLVER                 | mode of operation                                                               | String - `rpc`, `in-process` | rpc                           | rpc & in-process    |
   | host                  | FLAGD_HOST                     | remote host                                                                     | String                       | localhost                     | rpc & in-process    |
-  | port                  | FLAGD_PORT                     | remote port                                                                     | int                          | 8013 (rpc), 8015 (in-process) | rpc & in-process    |
+  | port                  | FLAGD_PORT (rpc), FLAGD_SYNC_PORT (in-process, FLAGD_PORT as fallback) | remote port                                                                     | int                          | 8013 (rpc), 8015 (in-process) | rpc & in-process    |
   | targetUri             | FLAGD_TARGET_URI               | alternative to host/port, supporting custom name resolution                     | string                       | null                          | rpc & in-process    |
   | tls                   | FLAGD_TLS                      | connection encryption                                                           | boolean                      | false                         | rpc & in-process    |
   | socketPath            | FLAGD_SOCKET_PATH              | alternative to host port, unix socket                                           | String                       | null                          | rpc & in-process    |
@@ -208,6 +208,16 @@ Feature: Configuration Test
       | tls    | FLAGD_TLS  | Boolean | True  |
       | port   | FLAGD_PORT | Integer | 1234  |
 
+    @in-process
+    Scenarios: In-Process Sync Port
+      | option | env             | type    | value |
+      | port   | FLAGD_SYNC_PORT | Integer | 1234  |
+
+    @in-process @legacy-sync-port
+    Scenarios: In-Process Legacy Port (backwards compatibility)
+      | option | env        | type    | value |
+      | port   | FLAGD_PORT | Integer | 1234  |
+
     @rpc @in-process @targetURI
     Scenarios: Target URI
       | option    | env              | type   | value |
@@ -284,6 +294,16 @@ Feature: Configuration Test
       | tls    | FLAGD_TLS  | Boolean | True  | False     |
       | port   | FLAGD_PORT | Integer | 1234  | 3456      |
 
+    @in-process
+    Scenarios: In-Process Sync Port
+      | option | env             | type    | value | env-value |
+      | port   | FLAGD_SYNC_PORT | Integer | 1234  | 3456      |
+
+    @in-process @legacy-sync-port
+    Scenarios: In-Process Legacy Port (backwards compatibility)
+      | option | env        | type    | value | env-value |
+      | port   | FLAGD_PORT | Integer | 1234  | 3456      |
+
     @rpc @in-process @targetURI
     Scenarios: Target URI
       | option    | env              | type   | value | env-value |
@@ -329,3 +349,10 @@ Feature: Configuration Test
     Scenarios: providerId
       | option     | env               | type   | value      | env-value  |
       | providerId | FLAGD_PROVIDER_ID | String | providerId | env-prov |
+
+  @in-process
+  Scenario: FLAGD_SYNC_PORT takes priority over FLAGD_PORT
+    Given an environment variable "FLAGD_SYNC_PORT" with value "9999"
+    And an environment variable "FLAGD_PORT" with value "8888"
+    When a config was initialized
+    Then the option "port" of type "Integer" should have the value "9999"