diff --git a/src/rpc.c b/src/rpc.c
index edfd9bf..5d31e85 100644
--- a/src/rpc.c
+++ b/src/rpc.c
@@ -236,6 +236,57 @@ exit:
   (void)fi;
 }
 
+static void rpc_timespec_replace_handler(struct mg_rpc_request_info *ri, void *cb_arg, struct mg_rpc_frame_info *fi, struct mg_str args) {
+  struct mgos_timespec *ts;
+  int   idx;
+  char *spec = NULL;
+  char  fn[100];
+
+  rpc_log(ri, args);
+
+  json_scanf(args.p, args.len, ri->args_fmt, &idx, &spec);
+  if (idx < 0 || idx >= channel_get_total()) {
+    mg_rpc_send_errorf(ri, 400, "idx must be between 0 and %d", channel_get_total() - 1);
+    ri = NULL;
+    goto exit;
+  }
+  ts = channel_get_timespec(idx);
+  if (!ts) {
+    mg_rpc_send_errorf(ri, 400, "timespec on channel %d isn't set", idx);
+    ri = NULL;
+    goto exit;
+  }
+  if (!timespec_clear_spec(ts)) {
+    mg_rpc_send_errorf(ri, 400, "Failed to clear timespec on channel %d", idx);
+    ri = NULL;
+    return;
+  }
+  channel_override_clear(idx);
+
+  if (!timespec_add_spec(ts, spec)) {
+    mg_rpc_send_errorf(ri, 400, "timespec '%Q' is malformed", spec);
+    ri = NULL;
+    goto exit;
+  }
+
+  snprintf(fn, sizeof(fn) - 1, "timespec.chan%d", idx);
+  if (!timespec_write_file(ts, fn)) {
+    mg_rpc_send_errorf(ri, 400, "Could not commit timespec to file: %s", fn);
+    ri = NULL;
+    return;
+  }
+
+  mg_rpc_send_responsef(ri, "{idx: %d}", idx);
+  ri = NULL;
+
+exit:
+  if (spec) {
+    free(spec);
+  }
+  (void)cb_arg;
+  (void)fi;
+}
+
 void rpc_init() {
   struct mg_rpc *c = mgos_rpc_get_global();
 
@@ -245,4 +296,5 @@ void rpc_init() {
   mg_rpc_add_handler(c, "Timespec.Get", "{idx: %d}", rpc_timespec_get_handler, NULL);
   mg_rpc_add_handler(c, "Timespec.Clear", "{idx: %d}", rpc_timespec_clear_handler, NULL);
   mg_rpc_add_handler(c, "Timespec.Add", "{idx: %d, spec: %Q}", rpc_timespec_add_handler, NULL);
+  mg_rpc_add_handler(c, "Timespec.Replace", "{idx: %d, spec: %Q}", rpc_timespec_replace_handler, NULL);
 }