diff --git a/src/afd.c b/src/afd.c
new file mode 100644
index 0000000..3a0cb41
--- /dev/null
+++ b/src/afd.c
@@ -0,0 +1,89 @@
+#include "afd.h"
+#include "error.h"
+#include "win.h"
+
+int afd_poll(SOCKET socket, AFD_POLL_INFO* info, OVERLAPPED* overlapped) {
+  IO_STATUS_BLOCK iosb;
+  IO_STATUS_BLOCK* iosb_ptr;
+  HANDLE event = NULL;
+  void* apc_context;
+  NTSTATUS status;
+  DWORD error;
+
+  if (overlapped != NULL) {
+    /* Overlapped operation. */
+    iosb_ptr = (IO_STATUS_BLOCK*) &overlapped->Internal;
+    event = overlapped->hEvent;
+
+    /* Do not report iocp completion if hEvent is tagged. */
+    if ((uintptr_t) event & 1) {
+      event = (HANDLE)((uintptr_t) event & ~(uintptr_t) 1);
+      apc_context = NULL;
+    } else {
+      apc_context = overlapped;
+    }
+
+  } else {
+    /* Blocking operation. */
+    iosb_ptr = &iosb;
+    event = CreateEventW(NULL, FALSE, FALSE, NULL);
+    if (event == NULL) {
+      return SOCKET_ERROR;
+    }
+    apc_context = NULL;
+  }
+
+  iosb_ptr->Status = STATUS_PENDING;
+  status = NtDeviceIoControlFile((HANDLE) socket,
+                                 event,
+                                 NULL,
+                                 apc_context,
+                                 iosb_ptr,
+                                 IOCTL_AFD_POLL,
+                                 info,
+                                 sizeof *info,
+                                 info,
+                                 sizeof *info);
+
+  if (overlapped == NULL) {
+    /* If this is a blocking operation, wait for the event to become
+     * signaled, and then grab the real status from the io status block.
+     */
+    if (status == STATUS_PENDING) {
+      DWORD r = WaitForSingleObject(event, INFINITE);
+
+      if (r == WAIT_FAILED) {
+        DWORD saved_error = GetLastError();
+        CloseHandle(event);
+        WSASetLastError(saved_error);
+        return SOCKET_ERROR;
+      }
+
+      status = iosb_ptr->Status;
+    }
+
+    CloseHandle(event);
+  }
+
+  switch (status) {
+    case STATUS_SUCCESS:
+      error = ERROR_SUCCESS;
+      break;
+
+    case STATUS_PENDING:
+      error = WSA_IO_PENDING;
+      break;
+
+    default:
+      error = we_map_ntstatus_to_winsock_error(status);
+      break;
+  }
+
+  WSASetLastError(error);
+
+  if (error == ERROR_SUCCESS) {
+    return 0;
+  } else {
+    return SOCKET_ERROR;
+  }
+}
diff --git a/src/afd.h b/src/afd.h
index 0b7e27e..67b325b 100644
--- a/src/afd.h
+++ b/src/afd.h
@@ -4,10 +4,6 @@
 #include "nt.h"
 #include "win.h"
 
-#ifndef SIO_BASE_HANDLE
-#define SIO_BASE_HANDLE 0x48000022
-#endif
-
 #ifndef FILE_DEVICE_NETWORK
 #define FILE_DEVICE_NETWORK 0x00000012
 #endif
@@ -86,4 +82,6 @@ static const GUID AFD_PROVIDER_IDS[] = {
      0x43e4,
      {0xb7, 0xbd, 0x18, 0x1f, 0x20, 0x89, 0x79, 0x2a}}};
 
+int afd_poll(SOCKET socket, AFD_POLL_INFO* info, OVERLAPPED* overlapped);
+
 #endif /* EPOLL_AFD_H_ */
diff --git a/src/epoll.c b/src/epoll.c
index 80496ac..0cb3618 100644
--- a/src/epoll.c
+++ b/src/epoll.c
@@ -10,6 +10,10 @@
 #include "tree.h"
 #include "win.h"
 
+#ifndef SIO_BASE_HANDLE
+#define SIO_BASE_HANDLE 0x48000022
+#endif
+
 #ifndef _SSIZE_T_DEFINED
 #define SSIZE_T_DEFINED
 typedef intptr_t ssize_t;
@@ -46,9 +50,6 @@ static int epoll__compare_sock_data(epoll_sock_data_t* a,
                                     epoll_sock_data_t* b);
 static int epoll__submit_poll_req(epoll_port_data_t* port_data,
                                   epoll_sock_data_t* sock_data);
-static int epoll__afd_poll(SOCKET socket,
-                           AFD_POLL_INFO* info,
-                           OVERLAPPED* overlapped);
 
 static int epoll__initialized = 0;
 
@@ -686,8 +687,8 @@ int epoll__submit_poll_req(epoll_port_data_t* port_data,
   io_req->poll_info.Handles[0].Status = 0;
   io_req->poll_info.Handles[0].Events = afd_events;
 
-  result = epoll__afd_poll(
-      sock_data->peer_sock, &io_req->poll_info, &io_req->overlapped);
+  result =
+      afd_poll(sock_data->peer_sock, &io_req->poll_info, &io_req->overlapped);
   if (result != 0) {
     DWORD error = WSAGetLastError();
     if (error != WSA_IO_PENDING) {
@@ -705,91 +706,3 @@ int epoll__submit_poll_req(epoll_port_data_t* port_data,
 
   return 0;
 }
-
-int epoll__afd_poll(SOCKET socket,
-                    AFD_POLL_INFO* info,
-                    OVERLAPPED* overlapped) {
-  IO_STATUS_BLOCK iosb;
-  IO_STATUS_BLOCK* iosb_ptr;
-  HANDLE event = NULL;
-  void* apc_context;
-  NTSTATUS status;
-  DWORD error;
-
-  if (overlapped != NULL) {
-    /* Overlapped operation. */
-    iosb_ptr = (IO_STATUS_BLOCK*) &overlapped->Internal;
-    event = overlapped->hEvent;
-
-    /* Do not report iocp completion if hEvent is tagged. */
-    if ((uintptr_t) event & 1) {
-      event = (HANDLE)((uintptr_t) event & ~(uintptr_t) 1);
-      apc_context = NULL;
-    } else {
-      apc_context = overlapped;
-    }
-
-  } else {
-    /* Blocking operation. */
-    iosb_ptr = &iosb;
-    event = CreateEventW(NULL, FALSE, FALSE, NULL);
-    if (event == NULL) {
-      return SOCKET_ERROR;
-    }
-    apc_context = NULL;
-  }
-
-  iosb_ptr->Status = STATUS_PENDING;
-  status = NtDeviceIoControlFile((HANDLE) socket,
-                                 event,
-                                 NULL,
-                                 apc_context,
-                                 iosb_ptr,
-                                 IOCTL_AFD_POLL,
-                                 info,
-                                 sizeof *info,
-                                 info,
-                                 sizeof *info);
-
-  if (overlapped == NULL) {
-    /* If this is a blocking operation, wait for the event to become
-     * signaled, and then grab the real status from the io status block.
-     */
-    if (status == STATUS_PENDING) {
-      DWORD r = WaitForSingleObject(event, INFINITE);
-
-      if (r == WAIT_FAILED) {
-        DWORD saved_error = GetLastError();
-        CloseHandle(event);
-        WSASetLastError(saved_error);
-        return SOCKET_ERROR;
-      }
-
-      status = iosb_ptr->Status;
-    }
-
-    CloseHandle(event);
-  }
-
-  switch (status) {
-    case STATUS_SUCCESS:
-      error = ERROR_SUCCESS;
-      break;
-
-    case STATUS_PENDING:
-      error = WSA_IO_PENDING;
-      break;
-
-    default:
-      error = we_map_ntstatus_to_winsock_error(status);
-      break;
-  }
-
-  WSASetLastError(error);
-
-  if (error == ERROR_SUCCESS) {
-    return 0;
-  } else {
-    return SOCKET_ERROR;
-  }
-}