diff --git a/srcpkgs/blackboxwm/patches/time64.patch b/srcpkgs/blackboxwm/patches/time64.patch
new file mode 100644
index 00000000000..9bbcf04b742
--- /dev/null
+++ b/srcpkgs/blackboxwm/patches/time64.patch
@@ -0,0 +1,11 @@
+--- src/Toolbar.cc	2020-12-13 23:57:20.285876509 +0100
++++ src/Toolbar.cc	2020-12-13 23:58:32.570856812 +0100
+@@ -44,7 +44,7 @@
+ {
+   timeval now;
+   gettimeofday(&now, 0);
+-  return (std::max(1000l, ((((resolution - (now.tv_sec % resolution)) * 1000l))
++  return (std::max(static_cast<uint64_t>(1000l), static_cast<uint64_t>((((resolution - (now.tv_sec % resolution)) * 1000l))
+                            - (now.tv_usec / 1000l))));
+ }
+