diff --git a/tests/scripts/checkcerts.sh b/tests/scripts/checkcerts.sh
index 5c3d737e46..72aa9c53bd 100755
--- a/tests/scripts/checkcerts.sh
+++ b/tests/scripts/checkcerts.sh
@@ -4,6 +4,9 @@
 # Returns nonzero on failure. Fails if cert cannot be read or is older than
 # $SOON (default 30).
 #
+# Hard dependency: OpenSSL OR gnutls
+# Recommended: GNU date
+#
 # zzz 2011-08
 # kytv 2013-03
 # public domain
@@ -22,17 +25,58 @@ elif [ $(which certtool) ]; then : ;else
     exit 1
 fi
 
-CHECKCERT() {
+# This "grouping hack" is here to prevent errors from being displayed with the
+# original Bourne shell (Linux shells don't need the {}s
+if { date --help;} >/dev/null 2>&1 ; then
+    HAVE_GNUDATE=1
+fi
+
+checkcert() {
     if [ $OPENSSL ]; then
         DATA=$(openssl x509 -enddate -noout -in $1| cut -d'=' -f2-)
     else
         DATA=$(certtool -i < "$1" | sed -e '/Not\sAfter/!d' -e 's/^.*:\s\(.*\)/\1/')
     fi
     # While this isn't strictly needed it'll ensure that the output is consistent,
-    # regardles of the tool used.
-    date -u -d "$(echo $DATA)" '+%F %H:%M'
+    # regardles of the tool used. Dates/times are formatting according to OpenSSL's output
+    # since this available by default on most systems.
+    if [ -n "$HAVE_GNUDATE" ]; then
+        LANG=C date -u -d "$(echo $DATA)" '+%b %d %H:%M:%S %Y GMT'
+    else
+        echo $DATA
+    fi
 }
 
+compute_dates() {
+    # Date computations currently depend on GNU date(1).
+    # If run on a non-Linux system just print the expiration date.
+    # TODO Cross-platform date calculation support
+    if [ -n "$HAVE_GNUDATE" ]; then
+        SECS=$(date -u -d "$EXPIRES" '+%s')
+        DAYS="$(expr \( $SECS - $NOW \) / 86400)"
+        if [ $DAYS -ge $SOON ]; then
+            echo "Expires in $DAYS days ($EXPIRES)"
+        elif [ $DAYS -eq 1 ]; then
+            DAYS=$(echo $DAYS | sed 's/^-//')
+            echo "****** Check for $I failed, expires tomorrow ($EXPIRES) ******"
+            FAIL=1
+        elif [ $DAYS -eq 0 ]; then
+            echo "****** Check for $i failed, expires today ($EXPIRES) ******"
+            FAIL=1
+        elif [ $DAYS -le $SOON ] && [ $DAYS -gt 0 ]; then
+            echo "****** Check for $i failed, expires in $DAYS days (<= ${SOON}d) ($EXPIRES) ******"
+            FAIL=1
+        elif [ $DAYS -lt $WARN ] && [ $DAYS -gt $SOON ]; then
+            echo "****** WARNING: $i expires in $DAYS days (<= ${WANT}d) ($EXPIRES) ******"
+        elif [ $DAYS -lt 0 ]; then
+            DAYS=$(echo $DAYS | sed 's/^-//')
+            echo "****** Check for $i failed, expired $DAYS days ago ($EXPIRES) ******"
+            FAIL=1
+        fi
+    else
+        echo $EXPIRES
+    fi
+}
 
 cd `dirname $0`/../../installer/resources/certificates
 
@@ -41,32 +85,12 @@ NOW=$(date -u '+%s')
 for i in *.crt
 do
     echo "Checking $i ..."
-    EXPIRES=`CHECKCERT $i`
+    EXPIRES=`checkcert $i`
     if [ -z "$EXPIRES" ]; then
         echo "********* FAILED CHECK FOR $i *************"
         FAIL=1
     else
-        SECS=$(date -u -d "$EXPIRES" '+%s')
-        DAYS="$(expr \( $SECS - $NOW \) / 86400)"
-        if [ $DAYS -ge $SOON ]; then
-            echo "Expires in $DAYS days ($EXPIRES)"
-        elif [ $DAYS -le $SOON ] && [ $DAYS -gt 0 ]; then
-            echo "****** Check for $i failed, expires in $DAYS days (<= ${SOON}d) ($EXPIRES) ******"
-            FAIL=1
-        elif [ $DAYS -le $WARN ] && [ $DAYS -ge $SOON ]; then
-            echo "****** WARNING: $i expires in $DAYS days (<= ${WANT}d) ($EXPIRES) ******"
-        elif [ $DAYS -eq 1 ]; then
-            DAYS=$(echo $DAYS | sed 's/^-//')
-            echo "****** Check for $I failed, expires in $DAYS day ($EXPIRES) ******"
-            FAIL=1
-        elif [ $DAYS -eq 0 ]; then
-            echo "****** Check for $i failed, expires today ($EXPIRES) ******"
-            FAIL=1
-        elif [ $DAYS -le 0 ]; then
-            DAYS=$(echo $DAYS | sed 's/^-//')
-            echo "****** Check for $i failed, expired $DAYS days ago ($EXPIRES) ******"
-            FAIL=1
-        fi
+       compute_dates
     fi
 done