diff --git a/openbsd b/openbsd
index d484188..4a13343 100755
--- a/openbsd
+++ b/openbsd
@@ -922,27 +922,30 @@ class Rlib:
         ls.append('')
         ls.append('. /etc/rc.d/rc.subr')
         ls.append('')
-
+        ls.append('safe_executable() {')
+        ls.append('    [ -x "$1" ] && [[ $((8#$(stat -f "%p" "$1") & 8#022)) == 0 ]] && [[ $(stat -f "%u" "$1") == 0 ]]')
+        ls.append('}')
+        ls.append('')
         ls.append('rc_start() {')
-        ls.append('   if [ -x "/etc/acme.pre" ]; then')
-        ls.append('       rc_exec "/etc/acme.pre"; _ret=$?')
-        ls.append('       if [[ ${_ret} != 0 ]]; then')
-        ls.append('           return ${_ret}')
-        ls.append('       fi')
-        ls.append('   fi')
+        ls.append('    if safe_executable "/etc/acme.pre"; then')
+        ls.append('        rc_exec "/etc/acme.pre"; _ret=$?')
+        ls.append('        if [[ ${_ret} != 0 ]]; then')
+        ls.append('            return ${_ret}')
+        ls.append('        fi')
+        ls.append('    fi')
         ls.append('')
-        ls.append('   rc_exec "${daemon} ${daemon_flags}"; _ret=$?')
-        ls.append('   ')
-        ls.append('   if [[ ${_ret} == 0 ]]; then')
-        ls.append('       if [ -x "/etc/acme.post" ]; then')
-        ls.append('           rc_exec "/etc/acme.post"; _ret=$?')
-        ls.append('           return ${_ret}')
-        ls.append('       fi')
-        ls.append('   elif [[ ${_ret} == 2 ]]; then')
-        ls.append('       return 0')
-        ls.append('   else')
-        ls.append('       return ${_ret}')
-        ls.append('   fi')
+        ls.append('    rc_exec "${daemon} ${daemon_flags}"; _ret=$?')
+        ls.append('    ')
+        ls.append('    if [[ ${_ret} == 0 ]]; then')
+        ls.append('        if safe_executable "/etc/acme.post"; then')
+        ls.append('            rc_exec "/etc/acme.post"; _ret=$?')
+        ls.append('            return ${_ret}')
+        ls.append('        fi')
+        ls.append('    elif [[ ${_ret} == 2 ]]; then')
+        ls.append('        return 0')
+        ls.append('    else')
+        ls.append('        return ${_ret}')
+        ls.append('    fi')
         ls.append('}')
         ls.append('')
         ls.append('rc_cmd $1')