diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index d45c2bd765..447e607436 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -217,7 +217,7 @@ UI
 VIMSCRIPT
 
 • |v:exitreason| is set before |QuitPre|.
-• |v:starttime| is the process start time (monotonic nanoseconds).
+• |v:starttime| is the process start time (nanoseconds from UNIX epoch).
 
 ==============================================================================
 CHANGED FEATURES                                                 *news-changed*
diff --git a/runtime/doc/vvars.txt b/runtime/doc/vvars.txt
index 6a885f6a4f..5d7efac2c8 100644
--- a/runtime/doc/vvars.txt
+++ b/runtime/doc/vvars.txt
@@ -635,11 +635,11 @@ v:stacktrace
 
 				*v:starttime* *starttime-variable*
 v:starttime
-		Timestamp (monotonic nanoseconds) when the Nvim process
+		Timestamp (nanoseconds from UNIX epoch) when the Nvim process
 		started.
 
 		To see the current "uptime": >lua
-		  vim.print(('uptime: %d seconds'):format((vim.uv.hrtime() - vim.v.starttime) / 1e9))
+		  vim.print(('uptime: %d seconds'):format(os.time() - (vim.v.starttime / 1e9)))
 <
 		Read-only.
 
diff --git a/runtime/lua/vim/_core/ex_cmd.lua b/runtime/lua/vim/_core/ex_cmd.lua
index bff960e39d..81232abf74 100644
--- a/runtime/lua/vim/_core/ex_cmd.lua
+++ b/runtime/lua/vim/_core/ex_cmd.lua
@@ -259,7 +259,9 @@ function M.ex_terminal(eap, shell_argv)
 end
 
 function M.ex_uptime()
-  local uptime = math.floor((uv.hrtime() - vim.v.starttime) / 1e9)
+  -- os.time() might lead to uptime == -1 when this is called too quickly after startup
+  local now = assert(uv.clock_gettime('realtime'))
+  local uptime = math.floor((now.sec * 1e9 + now.nsec - vim.v.starttime) / 1e9)
   local uptime_display = time.fmt_rtime(uptime)
   api.nvim_echo({ { N_('Up %s'):format(uptime_display) } }, true, {})
 end
diff --git a/runtime/lua/vim/_meta/vvars.gen.lua b/runtime/lua/vim/_meta/vvars.gen.lua
index 7b5ca0e417..bee771bc23 100644
--- a/runtime/lua/vim/_meta/vvars.gen.lua
+++ b/runtime/lua/vim/_meta/vvars.gen.lua
@@ -667,13 +667,13 @@ vim.v.shell_error = ...
 --- @type table[]
 vim.v.stacktrace = ...
 
---- Timestamp (monotonic nanoseconds) when the Nvim process
+--- Timestamp (nanoseconds from UNIX epoch) when the Nvim process
 --- started.
 ---
 --- To see the current "uptime":
 ---
 --- ```lua
----   vim.print(('uptime: %d seconds'):format((vim.uv.hrtime() - vim.v.starttime) / 1e9))
+---   vim.print(('uptime: %d seconds'):format(os.time() - (vim.v.starttime / 1e9)))
 --- ```
 ---
 --- Read-only.
diff --git a/src/nvim/main.c b/src/nvim/main.c
index a1320648a4..4cfec6bd41 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -197,7 +197,7 @@ void early_init(mparm_T *paramp)
   estack_init();
   cmdline_init();
   eval_init();          // init global variables
-  set_vim_var_nr(VV_STARTTIME, (varnumber_T)os_hrtime());
+  set_vim_var_nr(VV_STARTTIME, (varnumber_T)os_realtime());
   init_path(argv0 ? argv0 : "nvim");
   init_normal_cmds();   // Init the table of Normal mode commands.
   runtime_init();
diff --git a/src/nvim/os/time.c b/src/nvim/os/time.c
index f243eda047..2e6bf3e56d 100644
--- a/src/nvim/os/time.c
+++ b/src/nvim/os/time.c
@@ -32,6 +32,25 @@ uint64_t os_hrtime(void)
   return uv_hrtime();
 }
 
+/// Obtain the current system time from a high-resolution
+/// real-time clock source.
+///
+/// The real-time clock counts from the UNIX epoch (1970-01-01)
+/// and is subject to time adjustments; it can jump back in time.
+///
+/// @return Nanoseconds since epoch or 0
+int64_t os_realtime(void)
+  FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  uv_timespec64_t ts = { 0 };
+  int error_number;
+  if ((error_number = uv_clock_gettime(UV_CLOCK_REALTIME, &ts)) != 0) {
+    ELOG("uv_clock_gettime failed: %d %s", error_number, uv_err_name(error_number));
+    return 0;
+  }
+  return ts.tv_sec * 1000000000L + ts.tv_nsec;
+}
+
 /// Gets a millisecond-resolution, monotonically-increasing time relative to an
 /// arbitrary time in the past.
 ///
diff --git a/src/nvim/vvars.lua b/src/nvim/vvars.lua
index 648e5f1310..7096349125 100644
--- a/src/nvim/vvars.lua
+++ b/src/nvim/vvars.lua
@@ -756,11 +756,11 @@ M.vars = {
   starttime = {
     type = 'integer',
     desc = [=[
-      Timestamp (monotonic nanoseconds) when the Nvim process
+      Timestamp (nanoseconds from UNIX epoch) when the Nvim process
       started.
 
       To see the current "uptime": >lua
-        vim.print(('uptime: %d seconds'):format((vim.uv.hrtime() - vim.v.starttime) / 1e9))
+        vim.print(('uptime: %d seconds'):format(os.time() - (vim.v.starttime / 1e9)))
       <
       Read-only.
     ]=],