diff --git a/testssl.sh b/testssl.sh
index 9b47e4b9..b3ba588d 100755
--- a/testssl.sh
+++ b/testssl.sh
@@ -469,11 +469,15 @@ HAS_GNUDATE=false
 HAS_FREEBSDDATE=false
 HAS_OPENBSDDATE=false
 if date -d @735275209 >/dev/null 2>&1; then
-     if date -r @735275209  >/dev/null 2>&1; then
+     if date -r @735275209 >/dev/null 2>&1; then
+          # Ubuntu >= 25.10
+          HAS_GNUDATE=true
+     elif date -r 735275209 2>&1 | grep -q "No such file"; then
+          # e.g. Debian 24.04, Debian 11-13
+          HAS_GNUDATE=true
+     elif date -r 735275209 >/dev/null 2>&1; then
           # It can't do any conversion from a plain date output.
           HAS_OPENBSDDATE=true
-     else
-          HAS_GNUDATE=true
      fi
 fi
 # FreeBSD and OS X date(1) accept "-f inputformat", so do newer OpenBSD versions >~ 6.6.