diff --git a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
index f17d579b4..dacca37ed 100644
--- a/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
+++ b/src/Forms/GridField/GridFieldDetailForm_ItemRequest.php
@@ -454,7 +454,7 @@ class GridFieldDetailForm_ItemRequest extends RequestHandler
 
             $gridState = $this->gridField->getState(false);
             $actions->push(HiddenField::create($manager->getStateKey($this->gridField), null, $gridState));
-            if ($manager instanceof GridFieldStateStoreInterface) {
+            if (ClassInfo::hasMethod($manager, 'getStateRequestVar')) {
                 $stateRequestVar = $manager->getStateRequestVar();
                 $stateValue = $this->getRequest()->requestVar($stateRequestVar);
                 if ($stateValue) {
diff --git a/src/Forms/GridField/GridFieldStateStoreInterface.php b/src/Forms/GridField/GridFieldStateStoreInterface.php
deleted file mode 100644
index 2037ad8ea..000000000
--- a/src/Forms/GridField/GridFieldStateStoreInterface.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-namespace SilverStripe\Forms\GridField;
-
-interface GridFieldStateStoreInterface
-{
-    public function storeState(GridField $gridField, $value = null);
-
-    public function getStateRequestVar(): string;
-}
diff --git a/src/Forms/GridField/GridState_Data.php b/src/Forms/GridField/GridState_Data.php
index e5f80840b..a0761a5d8 100644
--- a/src/Forms/GridField/GridState_Data.php
+++ b/src/Forms/GridField/GridState_Data.php
@@ -2,6 +2,8 @@
 
 namespace SilverStripe\Forms\GridField;
 
+use SilverStripe\Core\ClassInfo;
+
 /**
  * Simple set of data, similar to stdClass, but without the notice-level
  * errors.
@@ -86,7 +88,7 @@ class GridState_Data
     public function storeData()
     {
         $stateManager = $this->getStateManager();
-        if ($stateManager instanceof GridFieldStateStoreInterface) {
+        if (ClassInfo::hasMethod($stateManager, 'storeState')) {
             $stateManager->storeState($this->state->getGridField(), $this->state->Value());
         }
     }
diff --git a/src/Forms/GridField/SessionGridFieldStateManager.php b/src/Forms/GridField/SessionGridFieldStateManager.php
index 750c1f336..4ed3133ea 100644
--- a/src/Forms/GridField/SessionGridFieldStateManager.php
+++ b/src/Forms/GridField/SessionGridFieldStateManager.php
@@ -11,7 +11,7 @@ use SilverStripe\Control\HTTPRequest;
  * (i.e. the state is changed from the default).
  * If a session state key is present in the request, it will always be used instead of generating a new one.
  */
-class SessionGridFieldStateManager implements GridFieldStateManagerInterface, GridFieldStateStoreInterface
+class SessionGridFieldStateManager implements GridFieldStateManagerInterface
 {
     protected static $state_ids = [];