diff --git a/core/base/inc/TPRegexp.h b/core/base/inc/TPRegexp.h
index 47817f7721ee3..6f8f954ea0859 100644
--- a/core/base/inc/TPRegexp.h
+++ b/core/base/inc/TPRegexp.h
@@ -18,11 +18,11 @@
 //                                                                      //
 // C++ Wrapper for the "Perl Compatible Regular Expressions" library    //
 //  The PCRE lib can be found at:                                       //
-//              http://www.pcre.org/                                    //
+//              https://www.pcre.org/                                    //
 //                                                                      //
 // Extensive documentation about Regular expressions in Perl can be     //
 // found at :                                                           //
-//              http://perldoc.perl.org/perlre.html                     //
+//              https://perldoc.perl.org/perlre.html                     //
 //                                                                      //
 //////////////////////////////////////////////////////////////////////////
 
diff --git a/core/base/inc/TQClass.h b/core/base/inc/TQClass.h
index 7469cd23e5ce8..495196562c240 100644
--- a/core/base/inc/TQClass.h
+++ b/core/base/inc/TQClass.h
@@ -16,7 +16,7 @@
 //                                                                      //
 // This is part of the ROOT implementation of the Qt object             //
 // communication mechanism (see also                                    //
-// http://www.troll.no/qt/metaobjects.html)                             //
+// https://www.troll.no/qt/metaobjects.html)                             //
 //                                                                      //
 // See TQObject for details.                                             //
 //                                                                      //
diff --git a/core/base/inc/TSystemDirectory.h b/core/base/inc/TSystemDirectory.h
index 16dfcf57896ad..3f0349c3b884f 100644
--- a/core/base/inc/TSystemDirectory.h
+++ b/core/base/inc/TSystemDirectory.h
@@ -19,7 +19,7 @@
 // Describes an Operating System directory for the browser.             //
 //                                                                      //
 // Author: Christian Bormann  30/09/97                                  //
-//         http://www.ikf.physik.uni-frankfurt.de/~bormann/             //
+//         https://www.ikf.physik.uni-frankfurt.de/~bormann/             //
 //                                                                      //
 //////////////////////////////////////////////////////////////////////////
 
diff --git a/core/base/inc/TUri.h b/core/base/inc/TUri.h
index b318b7f933391..a95670817b61d 100644
--- a/core/base/inc/TUri.h
+++ b/core/base/inc/TUri.h
@@ -18,7 +18,7 @@
 // TUri                                                                 //
 //                                                                      //
 // This class represents a RFC3986 compatible URI.                      //
-// See http://rfc.net/rfc3986.html.                                     //
+// See https://rfc.net/rfc3986.html.                                     //
 // It provides member functions to return the different parts of        //
 // an URI.                                                              //
 //                                                                      //
diff --git a/core/base/src/TPRegexp.cxx b/core/base/src/TPRegexp.cxx
index 215d192ee1eac..0fca685ba180b 100644
--- a/core/base/src/TPRegexp.cxx
+++ b/core/base/src/TPRegexp.cxx
@@ -13,10 +13,10 @@
 \ingroup Base
 
 C++ Wrapper for the "Perl Compatible Regular Expressions" library
- The PCRE lib can be found at: http://www.pcre.org/
+ The PCRE lib can be found at: https://www.pcre.org/
 
 Extensive documentation about Regular expressions in Perl can be
-found at : http://perldoc.perl.org/perlre.html
+found at : https://perldoc.perl.org/perlre.html
 */
 
 #include <iostream>
@@ -157,7 +157,7 @@ TPRegexp &TPRegexp::operator=(const TPRegexp &p)
 ///   Unlike i, m, s and x, these two flags affect the way the regex is used
 ///   rather than the regex itself. See Using regular expressions in Perl in
 ///   perlretut for further explanation of the g and c modifiers.
-/// For more detail see: http://perldoc.perl.org/perlre.html#Modifiers.
+/// For more detail see: https://perldoc.perl.org/perlre.html#Modifiers.
 
 UInt_t TPRegexp::ParseMods(const TString &modStr) const
 {
diff --git a/core/base/src/TQObject.cxx b/core/base/src/TQObject.cxx
index 27afeef569998..c0b9f057ea85e 100644
--- a/core/base/src/TQObject.cxx
+++ b/core/base/src/TQObject.cxx
@@ -13,7 +13,7 @@
 \ingroup Base
 
 This is the ROOT implementation of the Qt object communication
-mechanism (see also http://www.troll.no/qt/metaobjects.html)
+mechanism (see also https://www.troll.no/qt/metaobjects.html)
 
 Signals and slots are used for communication between objects.
 When an object has changed in some way that might be interesting