diff --git a/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp b/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
index 879a365..161ae95 100644
--- a/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
+++ b/fpdfsdk/cpdfsdk_annotiterator_embeddertest.cpp
@@ -40,7 +40,7 @@
   CFX_FloatRect RightTop(401, 401, 421, 421);
 
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      static_cast<CPDFSDK_FormFillEnvironment*>(form_handle());
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(form_handle());
 
   {
     // Page 0 specifies "row order".
diff --git a/fpdfsdk/cpdfsdk_helpers.h b/fpdfsdk/cpdfsdk_helpers.h
index 4fd85cf..5de947a 100644
--- a/fpdfsdk/cpdfsdk_helpers.h
+++ b/fpdfsdk/cpdfsdk_helpers.h
@@ -38,6 +38,7 @@
 class CPDF_StructTree;
 class CPDF_TextPage;
 class CPDF_TextPageFind;
+class CPDFSDK_FormFillEnvironment;
 class IPDFSDK_PauseAdapter;
 class FX_PATHPOINT;
 
@@ -197,6 +198,15 @@
   return reinterpret_cast<CPDF_TextPageFind*>(handle);
 }
 
+inline FPDF_FORMHANDLE FPDFFormHandleFromCPDFSDKFormFillEnvironment(
+    CPDFSDK_FormFillEnvironment* handle) {
+  return reinterpret_cast<FPDF_FORMHANDLE>(handle);
+}
+inline CPDFSDK_FormFillEnvironment*
+CPDFSDKFormFillEnvironmentFromFPDFFormHandle(FPDF_FORMHANDLE handle) {
+  return reinterpret_cast<CPDFSDK_FormFillEnvironment*>(handle);
+}
+
 ByteString CFXByteStringFromFPDFWideString(FPDF_WIDESTRING wide_string);
 
 #ifdef PDF_ENABLE_XFA
diff --git a/fpdfsdk/fpdf_formfill.cpp b/fpdfsdk/fpdf_formfill.cpp
index d529a5b..3a74bc3 100644
--- a/fpdfsdk/fpdf_formfill.cpp
+++ b/fpdfsdk/fpdf_formfill.cpp
@@ -143,14 +143,9 @@
 
 namespace {
 
-CPDFSDK_FormFillEnvironment* HandleToCPDFSDKEnvironment(
-    FPDF_FORMHANDLE handle) {
-  return static_cast<CPDFSDK_FormFillEnvironment*>(handle);
-}
-
 CPDFSDK_InterForm* FormHandleToInterForm(FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   return pFormFillEnv ? pFormFillEnv->GetInterForm() : nullptr;
 }
 
@@ -161,7 +156,7 @@
     return nullptr;
 
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   return pFormFillEnv ? pFormFillEnv->GetPageView(pPage, true) : nullptr;
 }
 
@@ -326,8 +321,10 @@
   // this and can just return the old Env. Otherwise, we'll end up setting a new
   // environment into the XFADocument and, that could get weird.
   auto* pContext = static_cast<CPDFXFA_Context*>(pDocument->GetExtension());
-  if (pContext && pContext->GetFormFillEnv())
-    return pContext->GetFormFillEnv();
+  if (pContext && pContext->GetFormFillEnv()) {
+    return FPDFFormHandleFromCPDFSDKFormFillEnvironment(
+        pContext->GetFormFillEnv());
+  }
 #endif
 
   auto pFormFillEnv = pdfium::MakeUnique<CPDFSDK_FormFillEnvironment>(
@@ -338,13 +335,14 @@
     pContext->SetFormFillEnv(pFormFillEnv.get());
 #endif  // PDF_ENABLE_XFA
 
-  return pFormFillEnv.release();  // Caller takes ownership.
+  return FPDFFormHandleFromCPDFSDKFormFillEnvironment(
+      pFormFillEnv.release());  // Caller takes ownership.
 }
 
 FPDF_EXPORT void FPDF_CALLCONV
 FPDFDOC_ExitFormFillEnvironment(FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return;
 
@@ -363,7 +361,7 @@
 FPDF_EXPORT void FPDF_CALLCONV FORM_SetSaveCallback(FPDF_FORMHANDLE hHandle,
                                                     FORM_SAVECALLED callback) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return;
 
@@ -558,7 +556,7 @@
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
 FORM_ForceToKillFocus(FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return false;
   return pFormFillEnv->KillFocusAnnot(0);
@@ -632,7 +630,7 @@
 FPDF_EXPORT void FPDF_CALLCONV FORM_OnBeforeClosePage(FPDF_PAGE page,
                                                       FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return;
 
@@ -651,7 +649,7 @@
 FPDF_EXPORT void FPDF_CALLCONV
 FORM_DoDocumentJSAction(FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (pFormFillEnv && pFormFillEnv->IsJSPlatformPresent())
     pFormFillEnv->ProcJavascriptFun();
 }
@@ -659,7 +657,7 @@
 FPDF_EXPORT void FPDF_CALLCONV
 FORM_DoDocumentOpenAction(FPDF_FORMHANDLE hHandle) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (pFormFillEnv && pFormFillEnv->IsJSPlatformPresent())
     pFormFillEnv->ProcOpenAction();
 }
@@ -667,7 +665,7 @@
 FPDF_EXPORT void FPDF_CALLCONV FORM_DoDocumentAAction(FPDF_FORMHANDLE hHandle,
                                                       int aaType) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return;
 
@@ -681,7 +679,8 @@
   if (aa.ActionExist(type)) {
     CPDF_Action action = aa.GetAction(type);
     CPDFSDK_ActionHandler* pActionHandler =
-        HandleToCPDFSDKEnvironment(hHandle)->GetActionHandler();
+        CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle)
+            ->GetActionHandler();
     pActionHandler->DoAction_Document(action, type, pFormFillEnv);
   }
 }
@@ -690,7 +689,7 @@
                                                   FPDF_FORMHANDLE hHandle,
                                                   int aaType) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv =
-      HandleToCPDFSDKEnvironment(hHandle);
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(hHandle);
   if (!pFormFillEnv)
     return;
 
diff --git a/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp b/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
index e4b329e..62d42f9 100644
--- a/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
+++ b/fpdfsdk/pwl/cpwl_combo_box_embeddertest.cpp
@@ -29,7 +29,8 @@
     m_page = LoadPage(0);
     ASSERT_TRUE(m_page);
 
-    m_pFormFillEnv = static_cast<CPDFSDK_FormFillEnvironment*>(form_handle());
+    m_pFormFillEnv =
+        CPDFSDKFormFillEnvironmentFromFPDFFormHandle(form_handle());
     CPDFSDK_AnnotIterator iter(m_pFormFillEnv->GetPageView(0),
                                CPDF_Annot::Subtype::WIDGET);
 
diff --git a/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp b/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
index 43d06d3..3edbf75 100644
--- a/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
+++ b/fpdfsdk/pwl/cpwl_edit_embeddertest.cpp
@@ -28,7 +28,8 @@
     m_page = LoadPage(0);
     ASSERT_TRUE(m_page);
 
-    m_pFormFillEnv = static_cast<CPDFSDK_FormFillEnvironment*>(form_handle());
+    m_pFormFillEnv =
+        CPDFSDKFormFillEnvironmentFromFPDFFormHandle(form_handle());
     CPDFSDK_AnnotIterator iter(m_pFormFillEnv->GetPageView(0),
                                CPDF_Annot::Subtype::WIDGET);
     // Normal text field.
diff --git a/fxjs/cjs_publicmethods_embeddertest.cpp b/fxjs/cjs_publicmethods_embeddertest.cpp
index 3860455..623ce68 100644
--- a/fxjs/cjs_publicmethods_embeddertest.cpp
+++ b/fxjs/cjs_publicmethods_embeddertest.cpp
@@ -180,7 +180,8 @@
   auto* page = LoadPage(0);
   ASSERT_TRUE(page);
 
-  CJS_Runtime runtime(static_cast<CPDFSDK_FormFillEnvironment*>(form_handle()));
+  CJS_Runtime runtime(
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(form_handle()));
   runtime.NewEventContext();
 
   WideString result;
@@ -214,7 +215,8 @@
   auto* page = LoadPage(0);
   ASSERT_TRUE(page);
 
-  CJS_Runtime runtime(static_cast<CPDFSDK_FormFillEnvironment*>(form_handle()));
+  CJS_Runtime runtime(
+      CPDFSDKFormFillEnvironmentFromFPDFFormHandle(form_handle()));
   runtime.NewEventContext();
 
   auto* handler = runtime.GetCurrentEventContext()->GetEventHandler();
diff --git a/public/fpdf_formfill.h b/public/fpdf_formfill.h
index 4a703d9..3381eed 100644
--- a/public/fpdf_formfill.h
+++ b/public/fpdf_formfill.h
@@ -10,8 +10,6 @@
 // NOLINTNEXTLINE(build/include)
 #include "fpdfview.h"
 
-typedef void* FPDF_FORMHANDLE;
-
 // These values are return values for a public API, so should not be changed
 // other than the count when adding new values.
 #define FORMTYPE_NONE 0            // Document contains no forms
diff --git a/public/fpdfview.h b/public/fpdfview.h
index a35e34a..ac109b9 100644
--- a/public/fpdfview.h
+++ b/public/fpdfview.h
@@ -44,6 +44,7 @@
 typedef const struct fpdf_dest_t__* FPDF_DEST;
 typedef struct fpdf_document_t__* FPDF_DOCUMENT;
 typedef struct fpdf_font_t__* FPDF_FONT;
+typedef struct fpdf_form_handle_t__* FPDF_FORMHANDLE;
 typedef struct fpdf_link_t__* FPDF_LINK;
 typedef struct fpdf_page_t__* FPDF_PAGE;
 typedef struct fpdf_pagelink_t__* FPDF_PAGELINK;