diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 7ab679a765d..7d05938feda 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -10422,10 +10422,14 @@ typedef struct PGoauthBearerRequest
 
     /* Hook outputs */
 
-    /* Callback implementing a custom asynchronous OAuth flow. */
+    /*
+     * Callback implementing a custom asynchronous OAuth flow. The signature is
+     * platform-dependent: PQ_SOCKTYPE is SOCKET on Windows, and int everywhere
+     * else.
+     */
     PostgresPollingStatusType (*async) (PGconn *conn,
                                         struct PGoauthBearerRequest *request,
-                                        SOCKTYPE *altsock);
+                                        PQ_SOCKTYPE *altsock);
 
     /* Callback to clean up custom allocations. */
     void        (*cleanup) (PGconn *conn, struct PGoauthBearerRequest *request);
@@ -10482,7 +10486,7 @@ typedef struct PGoauthBearerRequest
          hook. When the callback cannot make further progress without blocking,
          it should return either <symbol>PGRES_POLLING_READING</symbol> or
          <symbol>PGRES_POLLING_WRITING</symbol> after setting
-         <literal>*pgsocket</literal> to the file descriptor that will be marked
+         <literal>*altsock</literal> to the file descriptor that will be marked
          ready to read/write when progress can be made again. (This descriptor
          is then provided to the top-level polling loop via
          <function>PQsocket()</function>.) Return <symbol>PGRES_POLLING_OK</symbol>
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 0852584edae..877a6483b34 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -738,11 +738,15 @@ typedef struct _PGpromptOAuthDevice
 	int			expires_in;		/* seconds until user code expires */
 } PGpromptOAuthDevice;
 
-/* for PGoauthBearerRequest.async() */
+/*
+ * For PGoauthBearerRequest.async(). This macro just allows clients to avoid
+ * depending on libpq-int.h or Winsock for the "socket" type; it's undefined
+ * immediately below.
+ */
 #ifdef _WIN32
-#define SOCKTYPE uintptr_t		/* avoids depending on winsock2.h for SOCKET */
+#define PQ_SOCKTYPE uintptr_t	/* avoids depending on winsock2.h for SOCKET */
 #else
-#define SOCKTYPE int
+#define PQ_SOCKTYPE int
 #endif
 
 typedef struct PGoauthBearerRequest
@@ -768,10 +772,13 @@ typedef struct PGoauthBearerRequest
 	 * blocking during the original call to the PQAUTHDATA_OAUTH_BEARER_TOKEN
 	 * hook, it may be returned directly, but one of request->async or
 	 * request->token must be set by the hook.
+	 *
+	 * The (PQ_SOCKTYPE *) in the signature is a placeholder for the platform's
+	 * native socket type: (SOCKET *) on Windows, and (int *) everywhere else.
 	 */
 	PostgresPollingStatusType (*async) (PGconn *conn,
 										struct PGoauthBearerRequest *request,
-										SOCKTYPE * altsock);
+										PQ_SOCKTYPE * altsock);
 
 	/*
 	 * Callback to clean up custom allocations. A hook implementation may use
@@ -798,7 +805,7 @@ typedef struct PGoauthBearerRequest
 	void	   *user;
 } PGoauthBearerRequest;
 
-#undef SOCKTYPE
+#undef PQ_SOCKTYPE
 
 extern char *PQencryptPassword(const char *passwd, const char *user);
 extern char *PQencryptPasswordConn(PGconn *conn, const char *passwd, const char *user, const char *algorithm);