diff --git a/tools/log.sh b/tools/log.sh
index addcaeb7c..4fcda7f8a 100644
--- a/tools/log.sh
+++ b/tools/log.sh
@@ -5,14 +5,18 @@ CASENAME="$(pwd | xargs basename)"
 LOGFILE="$CASENAME.log"
 export LOGFILE
 
-STARTDATE="$(date --rfc-email)"
+rfc_email_date() {
+    date --rfc-email 2>/dev/null || date '+%a, %d %b %Y %H:%M:%S %z'
+}
+
+STARTDATE="$(rfc_email_date)"
 STARTTIME="$(date +%s)"
 echo "Started on: $STARTDATE" | tee "$CASENAME.log" 2>&1
 
 close_log() {
-    echo "Started on:  $STARTDATE" | tee --append "$LOGFILE" 2>&1
-    ENDDATE="$(date --rfc-email)"
+    echo "Started on: $STARTDATE" | tee -a "$LOGFILE" 2>&1
+    ENDDATE="$(rfc_email_date)"
     ENDTIME="$(date +%s)"
-    echo "Finished on: $ENDDATE" | tee --append "$LOGFILE" 2>&1
-    echo "Duration:    $((ENDTIME-STARTTIME)) seconds (wall-clock time, including time waiting for participants)" | tee --append "$LOGFILE" 2>&1
+    echo "Finished on: $ENDDATE" | tee -a "$LOGFILE" 2>&1
+    echo "Duration:    $((ENDTIME-STARTTIME)) seconds (wall-clock time, including time waiting for participants)" | tee -a "$LOGFILE" 2>&1
 }