--- src/unix/darwin.c
+++ src/unix/darwin.c
@@ -58,8 +58,16 @@
 
 
 uint64_t uv__hrtime(uv_clocktype_t type) {
+  uint64_t t;
   uv_once(&once, uv__hrtime_init_once);
-  return mach_continuous_time() * timebase.numer / timebase.denom;
+  t = mach_continuous_time();
+  /* On i386/x86_64/arm64 Macs timebase is 1/1 (or close), but on PowerPC the
+   * timebase runs at tens of MHz, making numer/denom ~= 1000000000/33333333:
+   * the naive t * numer overflows uint64_t after mere minutes of uptime,
+   * wrapping the clock backwards and starving every libuv timer. Split
+   * the scaling so no intermediate value can exceed 2^64. */
+  return (t / timebase.denom) * timebase.numer
+       + (t % timebase.denom) * timebase.numer / timebase.denom;
 }