diff --git a/bin/utils.sh b/bin/utils.sh
index 24a496de6..cb73b236e 100644
--- a/bin/utils.sh
+++ b/bin/utils.sh
@@ -5,14 +5,9 @@ export DEPTH=0
 verbose=${verbose:-false}
 profile=${profile:-false}
 
-if [[ "$OSTYPE" == "darwin"* ]]; then
-  DATE_CMD="gdate"
-else
-  DATE_CMD="date"
-fi
 
 time_now_ms () {
-  "$DATE_CMD" "+%s%3N"
+  perl -MTime::HiRes=time -e 'printf "%d\n", time*1000'
 }
 
 indented () {
diff --git a/nix/llvm-backend.nix b/nix/llvm-backend.nix
index 9c8fb1141..233c9d346 100644
--- a/nix/llvm-backend.nix
+++ b/nix/llvm-backend.nix
@@ -28,9 +28,6 @@ stdenv.mkDerivation {
       --replace 'extra_python_flags=()' \
                 'extra_python_flags=($(${python-env}/bin/pybind11-config --includes))'
 
-    substituteInPlace bin/utils.sh \
-      --replace 'gdate' 'date'
-
     substituteInPlace bin/llvm-kompile-clang \
       --replace 'uname' '${coreutils}/bin/uname' \
       --replace '"-lgmp"' '"-I${gmp.dev}/include" "-L${gmp}/lib" "-lgmp"' \