diff --git a/pkgs/tools/typesetting/tex/texlive/combine.nix b/pkgs/tools/typesetting/tex/texlive/combine.nix
index 645f9042bd5b..95c297650483 100644
--- a/pkgs/tools/typesetting/tex/texlive/combine.nix
+++ b/pkgs/tools/typesetting/tex/texlive/combine.nix
@@ -248,7 +248,11 @@ in (buildEnv {
     # libfaketime fixes non-determinism related to timestamps ignoring FORCE_SOURCE_DATE
     # we cannot fix further randomness caused by luatex; for further details, see
     # https://salsa.debian.org/live-team/live-build/-/blob/master/examples/hooks/reproducible/2006-reproducible-texlive-binaries-fmt-files.hook.chroot#L52
-    FORCE_SOURCE_DATE=1 TZ= faketime -f '@1980-01-01 00:00:00 x0.001' fmtutil --sys --all | grep '^fmtutil' # too verbose
+    # note that calling faketime and fmtutil is fragile (faketime uses LD_PRELOAD, fmtutil calls /bin/sh, causing potential glibc issues on non-NixOS)
+    # so we patch fmtutil to use faketime, rather than calling faketime fmtutil
+    substitute "$out/bin/fmtutil" fmtutil \
+      --replace 'my $cmdline = "$eng -ini ' 'my $cmdline = "faketime -f '"'"'\@1980-01-01 00:00:00 x0.001'"'"' $eng -ini '
+    FORCE_SOURCE_DATE=1 TZ= perl fmtutil --sys --all | grep '^fmtutil' # too verbose
     #texlinks "$out/bin" && wrapBin # do we need to regenerate format links?
 
     # Disable unavailable map files