diff --git a/pageant.c b/pageant.c
index ee386c7a..f82abe5f 100644
--- a/pageant.c
+++ b/pageant.c
@@ -1037,9 +1037,19 @@ static void pageant_conn_got_response(
     }
 }
 
+static bool pageant_conn_ask_passphrase(
+    PageantClient *pc, PageantClientDialogId *dlgid, const char *msg)
+{
+    struct pageant_conn_state *pcs =
+        container_of(pc, struct pageant_conn_state, pc);
+    return pageant_listener_client_ask_passphrase(pcs->plc, dlgid, msg);
+}
+
+
 static const struct PageantClientVtable pageant_connection_clientvt = {
     pageant_conn_log,
     pageant_conn_got_response,
+    pageant_conn_ask_passphrase,
 };
 
 static void pageant_conn_receive(
diff --git a/pageant.h b/pageant.h
index e80ef44d..3d58df33 100644
--- a/pageant.h
+++ b/pageant.h
@@ -15,6 +15,7 @@ typedef struct PageantClientVtable PageantClientVtable;
 typedef struct PageantClient PageantClient;
 typedef struct PageantClientInfo PageantClientInfo;
 typedef struct PageantClientRequestId PageantClientRequestId;
+typedef struct PageantClientDialogId PageantClientDialogId;
 struct PageantClient {
     const struct PageantClientVtable *vt;
     PageantClientInfo *info;    /* used by the central Pageant code */
@@ -32,6 +33,8 @@ struct PageantClientVtable {
                 const char *fmt, va_list ap);
     void (*got_response)(PageantClient *pc, PageantClientRequestId *reqid,
                          ptrlen response);
+    bool (*ask_passphrase)(PageantClient *pc, PageantClientDialogId *dlgid,
+                           const char *msg);
 };
 
 static inline void pageant_client_log_v(
@@ -54,6 +57,9 @@ static inline PRINTF_LIKE(3, 4) void pageant_client_log(
 static inline void pageant_client_got_response(
     PageantClient *pc, PageantClientRequestId *reqid, ptrlen response)
 { pc->vt->got_response(pc, reqid, response); }
+static inline bool pageant_client_ask_passphrase(
+    PageantClient *pc, PageantClientDialogId *dlgid, const char *msg)
+{ return pc->vt->ask_passphrase(pc, dlgid, msg); }
 
 /* PageantClientRequestId is used to match up responses to the agent
  * requests they refer to. A client may allocate one of these for each
@@ -91,6 +97,13 @@ void pageant_unregister_client(PageantClient *pc);
 void pageant_handle_msg(PageantClient *pc, PageantClientRequestId *reqid,
                         ptrlen msg);
 
+/*
+ * Send the core Pageant code a response to a passphrase request.
+ */
+void pageant_passphrase_request_success(PageantClientDialogId *dlgid,
+                                        ptrlen passphrase);
+void pageant_passphrase_request_refused(PageantClientDialogId *dlgid);
+
 /*
  * Construct a list of public keys, just as the two LIST_IDENTITIES
  * requests would have returned them.
@@ -145,6 +158,8 @@ struct PageantListenerClient {
 };
 struct PageantListenerClientVtable {
     void (*log)(PageantListenerClient *, const char *fmt, va_list ap);
+    bool (*ask_passphrase)(PageantListenerClient *pc,
+                           PageantClientDialogId *dlgid, const char *msg);
 };
 
 static inline void pageant_listener_client_log_v(
@@ -163,6 +178,9 @@ static inline PRINTF_LIKE(2, 3) void pageant_listener_client_log(
         va_end(ap);
     }
 }
+static inline bool pageant_listener_client_ask_passphrase(
+    PageantListenerClient *plc, PageantClientDialogId *dlgid, const char *msg)
+{ return plc->vt->ask_passphrase(plc, dlgid, msg); }
 
 struct pageant_listen_state;
 struct pageant_listen_state *pageant_listener_new(
diff --git a/unix/uxpgnt.c b/unix/uxpgnt.c
index 594fd716..0f4027e4 100644
--- a/unix/uxpgnt.c
+++ b/unix/uxpgnt.c
@@ -44,8 +44,16 @@ static void uxpgnt_log(PageantListenerClient *plc, const char *fmt, va_list ap)
     fprintf(pageant_logfp, "\n");
 }
 
+static bool uxpgnt_ask_passphrase(
+    PageantListenerClient *plc, PageantClientDialogId *dlgid, const char *msg)
+{
+    /* FIXME: we don't yet support dialog boxes */
+    return false;
+}
+
 static const PageantListenerClientVtable uxpgnt_vtable = {
     uxpgnt_log,
+    uxpgnt_ask_passphrase,
 };
 
 /*
diff --git a/windows/winpgnt.c b/windows/winpgnt.c
index d8c95109..345cfbe3 100644
--- a/windows/winpgnt.c
+++ b/windows/winpgnt.c
@@ -792,9 +792,17 @@ static void wm_copydata_got_response(
     SetEvent(wmct.ev_reply_ready);
 }
 
+static bool wm_copydata_ask_passphrase(
+    PageantClient *pc, PageantClientDialogId *dlgid, const char *msg)
+{
+    /* FIXME: we don't yet support dialog boxes */
+    return false;
+}
+
 static const PageantClientVtable wmcpc_vtable = {
     NULL, /* no logging in this client */
     wm_copydata_got_response,
+    wm_copydata_ask_passphrase,
 };
 
 static char *answer_filemapping_message(const char *mapname)
@@ -1176,11 +1184,19 @@ void cleanup_exit(int code)
     exit(code);
 }
 
+static bool winpgnt_listener_ask_passphrase(
+    PageantListenerClient *plc, PageantClientDialogId *dlgid, const char *msg)
+{
+    /* FIXME: we don't yet support dialog boxes */
+    return false;
+}
+
 struct winpgnt_client {
     PageantListenerClient plc;
 };
 static const PageantListenerClientVtable winpgnt_vtable = {
     NULL, /* no logging */
+    winpgnt_listener_ask_passphrase,
 };
 
 static struct winpgnt_client wpc[1];