diff --git a/modules/ldapbackend/exceptions.hh b/modules/ldapbackend/exceptions.hh
index 3436e38d1824..2e7ca6f4bf6e 100644
--- a/modules/ldapbackend/exceptions.hh
+++ b/modules/ldapbackend/exceptions.hh
@@ -17,13 +17,12 @@
  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#pragma once
+
 #include <exception>
 #include <stdexcept>
 #include <string>
 
-#ifndef LDAPEXCEPTIONS_HH
-#define LDAPEXCEPTIONS_HH
-
 class LDAPException : public std::runtime_error
 {
   public:
@@ -48,4 +47,3 @@ class LDAPNoSuchObject : public LDAPException
     explicit LDAPNoSuchObject() : LDAPException( "No such object" ) {}
 };
 
-#endif // LDAPEXCEPTIONS_HH
diff --git a/modules/ldapbackend/ldapauthenticator.hh b/modules/ldapbackend/ldapauthenticator.hh
index d8452a08b76e..53d22bed4a4d 100644
--- a/modules/ldapbackend/ldapauthenticator.hh
+++ b/modules/ldapbackend/ldapauthenticator.hh
@@ -16,6 +16,8 @@
  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#pragma once
+
 #include <ldap.h>
 #include <string>
 
@@ -23,9 +25,6 @@
 #include <config.h>
 #endif
 
-#ifndef LDAPAUTHENTICATOR_HH
-#define LDAPAUTHENTICATOR_HH
-
 class LdapAuthenticator
 {
   public:
@@ -34,4 +33,3 @@ class LdapAuthenticator
     virtual std::string getError() const = 0;
 };
 
-#endif // LDAPAUTHENTICATOR_HH
diff --git a/modules/ldapbackend/ldapauthenticator_p.hh b/modules/ldapbackend/ldapauthenticator_p.hh
index cd5d083eed9e..5cf8d412008a 100644
--- a/modules/ldapbackend/ldapauthenticator_p.hh
+++ b/modules/ldapbackend/ldapauthenticator_p.hh
@@ -16,12 +16,11 @@
  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#pragma once
+
 #include <krb5.h>
 #include "ldapauthenticator.hh"
 
-#ifndef LDAPAUTHENTICATOR_P_HH
-#define LDAPAUTHENTICATOR_P_HH
-
 #ifndef HAVE_KRB5_GET_INIT_CREDS_OPT_SET_DEFAULT_FLAGS
 #define krb5_get_init_creds_opt_set_default_flags( a, b, c, d ) /* This does not exist with MIT Kerberos */
 #endif
@@ -69,4 +68,3 @@ class LdapGssapiAuthenticator : public LdapAuthenticator
     virtual std::string getError() const;
 };
 
-#endif // LDAPAUTHENTICATOR_P_HH
diff --git a/modules/ldapbackend/ldapbackend.hh b/modules/ldapbackend/ldapbackend.hh
index f89e29af22d2..e0589ff2aa54 100644
--- a/modules/ldapbackend/ldapbackend.hh
+++ b/modules/ldapbackend/ldapbackend.hh
@@ -20,6 +20,9 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
+
+#pragma once
+
 #include <algorithm>
 #include <sstream>
 #include <utility>
@@ -39,10 +42,6 @@
 #include "utils.hh"
 
 
-
-#ifndef LDAPBACKEND_HH
-#define LDAPBACKEND_HH
-
 using std::string;
 using std::vector;
 
@@ -184,4 +183,3 @@ class LdapBackend : public DNSBackend
     void setNotified( uint32_t id, uint32_t serial ) override;
 };
 
-#endif /* LDAPBACKEND_HH */
diff --git a/modules/ldapbackend/ldaputils.hh b/modules/ldapbackend/ldaputils.hh
index 83012f234f72..5b1bc7a21849 100644
--- a/modules/ldapbackend/ldaputils.hh
+++ b/modules/ldapbackend/ldaputils.hh
@@ -17,14 +17,13 @@
  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
+#pragma once
+
 #include "exceptions.hh"
 
 #include <ldap.h>
 #include <string>
 
-#ifndef LDAPUTILS_HH
-#define LDAPUTILS_HH
-
 void ldapSetOption( LDAP *conn, int option, void *value );
 
 void ldapGetOption( LDAP *conn, int option, void *value );
@@ -33,4 +32,3 @@ std::string ldapGetError( LDAP *conn, int code );
 
 int ldapWaitResult( LDAP *conn, int msgid, int timeout, LDAPMessage** result = NULL );
 
-#endif // LDAPUTILS_HH
diff --git a/modules/ldapbackend/powerldap.hh b/modules/ldapbackend/powerldap.hh
index 8ff3441df306..4c7e8ff2c06c 100644
--- a/modules/ldapbackend/powerldap.hh
+++ b/modules/ldapbackend/powerldap.hh
@@ -20,6 +20,8 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
+#pragma once
+
 #include <list>
 #include <map>
 #include <memory>
@@ -31,12 +33,6 @@
 #include <lber.h>
 #include <ldap.h>
 
-
-
-
-#ifndef POWERLDAP_HH
-#define POWERLDAP_HH
-
 using std::list;
 using std::map;
 using std::string;
@@ -100,6 +96,3 @@ class PowerLDAP
     static const string escape( const string& tobe );
 };
 
-
-
-#endif
diff --git a/modules/ldapbackend/utils.hh b/modules/ldapbackend/utils.hh
index 902c3d53251d..7fc99fbb7e77 100644
--- a/modules/ldapbackend/utils.hh
+++ b/modules/ldapbackend/utils.hh
@@ -19,6 +19,9 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
+
+#pragma once
+
 #include <string>
 #include <vector>
 #include <time.h>
@@ -26,10 +29,6 @@
 #include "pdns/misc.hh"
 #include "pdns/utility.hh"
 
-
-#ifndef LDAPBACKEND_UTILS_HH
-#define LDAPBACKEND_UTILS_HH
-
 using std::string;
 using std::vector;
 
@@ -174,4 +173,3 @@ inline time_t str2tstamp( const string& str )
   return 0;
 }
 
-#endif
diff --git a/pdns/misc.cc b/pdns/misc.cc
index ab2ea0c6869b..c44d674be90c 100644
--- a/pdns/misc.cc
+++ b/pdns/misc.cc
@@ -197,10 +197,11 @@ size_t writen2WithTimeout(int fd, const void * buffer, size_t len, int timeout)
 string nowTime()
 {
   time_t now = time(nullptr);
-  struct tm* tm = localtime(&now);
+  struct tm tm;
+  localtime_r(&now, &tm);
   char buffer[30];
   // YYYY-mm-dd HH:MM:SS TZOFF
-  strftime(buffer, sizeof(buffer), "%F %T %z", tm);
+  strftime(buffer, sizeof(buffer), "%F %T %z", &tm);
   buffer[sizeof(buffer)-1] = '\0';
   return string(buffer);
 }
diff --git a/pdns/syncres.cc b/pdns/syncres.cc
index 7e2c548d7744..627c467fcc07 100644
--- a/pdns/syncres.cc
+++ b/pdns/syncres.cc
@@ -414,7 +414,8 @@ uint64_t SyncRes::doEDNSDump(int fd)
   fprintf(fp.get(),"; edns from thread follows\n;\n");
   for(const auto& eds : t_sstorage.ednsstatus) {
     count++;
-    fprintf(fp.get(), "%s\t%d\t%s", eds.first.toString().c_str(), (int)eds.second.mode, ctime(&eds.second.modeSetAt));
+    char tmp[26];
+    fprintf(fp.get(), "%s\t%d\t%s", eds.first.toString().c_str(), (int)eds.second.mode, ctime_r(&eds.second.modeSetAt, tmp));
   }
   return count;
 }
@@ -456,8 +457,9 @@ uint64_t SyncRes::doDumpThrottleMap(int fd)
   for(const auto& i : throttleMap)
   {
     count++;
+    char tmp[26];
     // remote IP, dns name, qtype, count, ttd
-    fprintf(fp.get(), "%s\t%s\t%d\t%u\t%s", i.first.get<0>().toString().c_str(), i.first.get<1>().toLogString().c_str(), i.first.get<2>(), i.second.count, ctime(&i.second.ttd));
+    fprintf(fp.get(), "%s\t%s\t%d\t%u\t%s", i.first.get<0>().toString().c_str(), i.first.get<1>().toLogString().c_str(), i.first.get<2>(), i.second.count, ctime_r(&i.second.ttd, tmp));
   }
 
   return count;
diff --git a/pdns/tsigutils.hh b/pdns/tsigutils.hh
index bffd0971d73f..3b5c926651d9 100644
--- a/pdns/tsigutils.hh
+++ b/pdns/tsigutils.hh
@@ -20,7 +20,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#pragma once
+
 #include "dnsname.hh"
 #include <string>
 
 std::string makeTSIGKey(const DNSName& algorithm);
+