diff --git a/network/netplay/netplay.c b/network/netplay/netplay.c
index d82108f640..53ebcffed3 100644
--- a/network/netplay/netplay.c
+++ b/network/netplay/netplay.c
@@ -822,15 +822,47 @@ static int poll_input(netplay_t *netplay, bool block)
  * netplay_simulate_input:
  * @netplay             : pointer to netplay object
  * @sim_ptr             : frame index for which to simulate input
+ * @resim               : are we resimulating, or simulating this frame for the
+ *                        first time?
  *
  * "Simulate" input by assuming it hasn't changed since the last read input.
  */
-void netplay_simulate_input(netplay_t *netplay, uint32_t sim_ptr)
+void netplay_simulate_input(netplay_t *netplay, uint32_t sim_ptr, bool resim)
 {
    size_t prev = PREV_PTR(netplay->read_ptr);
-   memcpy(netplay->buffer[sim_ptr].simulated_input_state,
-         netplay->buffer[prev].real_input_state,
-         sizeof(netplay->buffer[prev].real_input_state));
+   struct delta_frame *pframe = &netplay->buffer[prev],
+                      *simframe = &netplay->buffer[sim_ptr];
+   if (resim)
+   {
+      /* In resimulation mode, we only copy the buttons. The reason for this
+       * is nonobvious:
+       *
+       * If we resimulated nothing, then the /duration/ with which any input
+       * was pressed would be approximately correct, since the original
+       * simulation came in as the input came in, but the /number of times/
+       * the input was pressed would be wrong, as there would be an
+       * advancing wavefront of real data overtaking the simulated data
+       * (which is really just real data offset by some frames).
+       *
+       * That's acceptable for arrows in most situations, since the amount
+       * you move is tied to the duration, but unacceptable for buttons,
+       * which will seem to jerkily be pressed numerous times with those
+       * wavefronts.
+       */
+      const uint32_t keep = (1U<<RETRO_DEVICE_ID_JOYPAD_UP) |
+                            (1U<<RETRO_DEVICE_ID_JOYPAD_DOWN) |
+                            (1U<<RETRO_DEVICE_ID_JOYPAD_LEFT) |
+                            (1U<<RETRO_DEVICE_ID_JOYPAD_RIGHT);
+      uint32_t sim_state = simframe->simulated_input_state[0] & keep;
+      sim_state |= pframe->real_input_state[0] & ~keep;
+      simframe->simulated_input_state[0] = sim_state;
+   }
+   else
+   {
+      memcpy(simframe->simulated_input_state,
+             pframe->real_input_state,
+             sizeof(pframe->real_input_state));
+   }
 }
 
 
@@ -874,7 +906,7 @@ static bool netplay_poll(void)
 
    /* Simulate the input if we don't have real input */
    if (!netplay_data->buffer[netplay_data->self_ptr].have_remote)
-      netplay_simulate_input(netplay_data, netplay_data->self_ptr);
+      netplay_simulate_input(netplay_data, netplay_data->self_ptr, false);
 
    /* Consider stalling */
    switch (netplay_data->stall)
diff --git a/network/netplay/netplay_net.c b/network/netplay/netplay_net.c
index f9cb1c549f..f90d2362ef 100644
--- a/network/netplay/netplay_net.c
+++ b/network/netplay/netplay_net.c
@@ -280,7 +280,7 @@ static void netplay_net_post_frame(netplay_t *netplay)
 
          /* Simulate this frame's input */
          if (netplay->replay_frame_count >= netplay->read_frame_count)
-            netplay_simulate_input(netplay, netplay->replay_ptr);
+            netplay_simulate_input(netplay, netplay->replay_ptr, true);
 
          autosave_lock();
          core_run();
diff --git a/network/netplay/netplay_private.h b/network/netplay/netplay_private.h
index e8bf108da7..faff16b4a2 100644
--- a/network/netplay/netplay_private.h
+++ b/network/netplay/netplay_private.h
@@ -234,7 +234,7 @@ bool netplay_init_serialization(netplay_t *netplay);
 /* Force serialization to be ready by fast-forwarding the core */
 bool netplay_wait_and_init_serialization(netplay_t *netplay);
 
-void netplay_simulate_input(netplay_t *netplay, uint32_t sim_ptr);
+void netplay_simulate_input(netplay_t *netplay, uint32_t sim_ptr, bool resim);
 
 void   netplay_log_connection(const struct sockaddr_storage *their_addr,
       unsigned slot, const char *nick);