diff --git a/Changes b/Changes
index 795831731abe..e5e0f439ec86 100644
--- a/Changes
+++ b/Changes
@@ -140,6 +140,10 @@ Working version
 - #13740: Improve performance of Weak.find_aux
   (Josh Berdine, review by Gabriel Scherer)
 
+- #?????: Fix caml_win32_clock overflowing if wall-clock time exceeds
+  24.8 days.
+  (Antonin Décimo, review by ???)
+
 ### Other libraries:
 
 * #13376: Allow Dynlink.loadfile_private to load bytecode libraries with
diff --git a/otherlibs/unix/times_unix.c b/otherlibs/unix/times_unix.c
index 025eb33257f4..ef4fdf83fa82 100644
--- a/otherlibs/unix/times_unix.c
+++ b/otherlibs/unix/times_unix.c
@@ -60,7 +60,8 @@ CAMLprim value caml_unix_times(value unit)
   value res;
   struct tms buffer;
 
-  times(&buffer);
+  clock_t ret = times(&buffer);
+  if (ret == (clock_t) (-1)) caml_uerror("times", Nothing);
   res = caml_alloc_small(4 * Double_wosize, Double_array_tag);
   Store_double_flat_field(res, 0, (double) buffer.tms_utime / CLK_TCK);
   Store_double_flat_field(res, 1, (double) buffer.tms_stime / CLK_TCK);
diff --git a/otherlibs/unix/times_win32.c b/otherlibs/unix/times_win32.c
index 311d20e7744f..81dc408d31b5 100644
--- a/otherlibs/unix/times_win32.c
+++ b/otherlibs/unix/times_win32.c
@@ -13,12 +13,11 @@
 /*                                                                        */
 /**************************************************************************/
 
+#define CAML_INTERNALS
 #include <caml/mlvalues.h>
 #include <caml/alloc.h>
 #include "caml/unixsupport.h"
 #include <windows.h>
-
-#define CAML_INTERNALS
 #include <caml/winsupport.h>
 
 value caml_unix_times(value unit) {
@@ -33,8 +32,8 @@ value caml_unix_times(value unit) {
   }
 
   res = caml_alloc_small(4 * Double_wosize, Double_array_tag);
-  Store_double_flat_field(res, 0, (double)(utime.ul / 1e7));
-  Store_double_flat_field(res, 1, (double)(stime.ul / 1e7));
+  Store_double_flat_field(res, 0, (double) utime.ul / (NSEC_PER_SEC / 100));
+  Store_double_flat_field(res, 1, (double) stime.ul / (NSEC_PER_SEC / 100));
   Store_double_flat_field(res, 2, 0);
   Store_double_flat_field(res, 3, 0);
   return res;
diff --git a/runtime/caml/osdeps.h b/runtime/caml/osdeps.h
index 5dd42bbd8b3b..91c29321647a 100644
--- a/runtime/caml/osdeps.h
+++ b/runtime/caml/osdeps.h
@@ -133,6 +133,7 @@ CAMLextern int caml_win32_isatty(int fd);
 CAMLextern void caml_expand_command_line (int *, wchar_t ***);
 
 CAMLextern clock_t caml_win32_clock(void);
+CAMLextern uint64_t caml_win32_clock_100nsec(void);
 
 CAMLextern value caml_win32_xdg_defaults(void);
 
diff --git a/runtime/sys.c b/runtime/sys.c
index 9ad5bc6acb32..3d7db5506c8b 100644
--- a/runtime/sys.c
+++ b/runtime/sys.c
@@ -543,7 +543,7 @@ CAMLprim value caml_sys_system_command(value command)
 
 double caml_sys_time_include_children_unboxed(value include_children)
 {
-#ifdef HAS_GETRUSAGE
+#if defined(HAS_GETRUSAGE)
   struct rusage ru;
   double sec = 0.;
 
@@ -558,28 +558,31 @@ double caml_sys_time_include_children_unboxed(value include_children)
   }
 
   return sec;
-#else
-  #ifdef HAS_TIMES
-    #ifndef CLK_TCK
-      #ifdef HZ
-        #define CLK_TCK HZ
-      #else
-        #define CLK_TCK 60
-      #endif
+#elif defined(HAS_TIMES)
+  #ifndef CLK_TCK
+    #ifdef HZ
+      #define CLK_TCK HZ
+    #else
+      #define CLK_TCK 60
     #endif
-    struct tms t;
-    clock_t acc = 0;
-    times(&t);
-    acc += t.tms_utime + t.tms_stime;
-    if (Bool_val(include_children)) {
-      acc += t.tms_cutime + t.tms_cstime;
-    }
-    return (double)acc / CLK_TCK;
-  #else
-    /* clock() is standard ANSI C. We have no way of getting
-       subprocess times in this branch. */
-    return (double)clock_os() / CLOCKS_PER_SEC;
   #endif
+  struct tms t;
+  clock_t ticks = times(&t);
+  if (ticks == (clock_t) (-1)) return -1.;
+  ticks = t.tms_utime + t.tms_stime;
+  if (Bool_val(include_children)) {
+    ticks += t.tms_cutime + t.tms_cstime;
+  }
+  return (double) ticks / CLK_TCK;
+#elif defined(_WIN32)
+  /* We have no way of getting subprocess times in this branch. */
+  uint64_t t = caml_win32_clock_100nsec();
+  return t == UINT64_MAX ? -1. : (double) t / (NSEC_PER_SEC / 100);
+#else
+  /* clock() is standard ANSI C. We have no way of getting subprocess
+     times in this branch. */
+  clock_t ticks = clock_os();
+  return ticks == (clock_t) (-1) ? -1. : (double) ticks / CLOCKS_PER_SEC;
 #endif
 }
 
diff --git a/runtime/win32.c b/runtime/win32.c
index 1ead90d3d5d3..24bf4915c473 100644
--- a/runtime/win32.c
+++ b/runtime/win32.c
@@ -1135,16 +1135,30 @@ CAMLexport clock_t caml_win32_clock(void)
 {
   FILETIME _creation, _exit;
   CAML_ULONGLONG_FILETIME stime, utime;
-  ULONGLONG clocks_per_sec;
 
   if (!(GetProcessTimes(GetCurrentProcess(), &_creation, &_exit,
                         &stime.ft, &utime.ft))) {
-    return (clock_t)(-1);
+    return (clock_t) (-1);
   }
 
   /* total in 100-nanosecond intervals (1e7 / CLOCKS_PER_SEC) */
-  clocks_per_sec = 10000000ULL / (ULONGLONG)CLOCKS_PER_SEC;
-  return (clock_t)((stime.ul + utime.ul) / clocks_per_sec);
+  uint64_t ticks =
+    (stime.ul + utime.ul) / (NSEC_PER_SEC / 100 / CLOCKS_PER_SEC);
+  return ticks >= LONG_MAX ? (clock_t) (-1) : (clock_t) ticks;
+}
+
+CAMLexport uint64_t caml_win32_clock_100nsec(void)
+{
+  FILETIME _creation, _exit;
+  CAML_ULONGLONG_FILETIME stime, utime;
+
+  if (!(GetProcessTimes(GetCurrentProcess(), &_creation, &_exit,
+                        &stime.ft, &utime.ft))) {
+    return UINT64_MAX;
+  }
+
+  /* total in 100-nanosecond intervals */
+  return stime.ul + utime.ul;
 }
 
 static double clock_period_nsec = 0;