diff --git a/src/USER-MISC/fix_filter_corotate.cpp b/src/USER-MISC/fix_filter_corotate.cpp
index 4a04cea432..1bcf3cee21 100644
--- a/src/USER-MISC/fix_filter_corotate.cpp
+++ b/src/USER-MISC/fix_filter_corotate.cpp
@@ -57,7 +57,7 @@ static const char cite_filter_corotate[] =
   " Doi = {https://doi.org/10.1016/j.jcp.2016.12.024},\n"
   " ISSN = {0021-9991},\n"
   " Keywords = {Mollified impulse method},\n"
-  " Url = {http://www.sciencedirect.com/science/article/pii/S0021999116306787}\n"
+  " Url = {https://www.sciencedirect.com/science/article/pii/S0021999116306787}\n"
   "}\n\n";
 
 /* ---------------------------------------------------------------------- */
diff --git a/src/USER-MISC/fix_ipi.cpp b/src/USER-MISC/fix_ipi.cpp
index 56c313c497..7fb696ce8c 100644
--- a/src/USER-MISC/fix_ipi.cpp
+++ b/src/USER-MISC/fix_ipi.cpp
@@ -40,7 +40,7 @@ using namespace FixConst;
  * Ceriotti, M., More, J., & Manolopoulos, D. E. (2014).
  * i-PI: A Python interface for ab initio path integral molecular dynamics simulations.
  * Computer Physics Communications, 185, 1019–1026. doi:10.1016/j.cpc.2013.10.027
- * And see [http://github.com/i-pi/i-pi] to download a version of i-PI
+ * And see [https://github.com/i-pi/i-pi] to download a version of i-PI
  ******************************************************************************************/
 
 // socket interface
diff --git a/src/USER-MISC/fix_rhok.cpp b/src/USER-MISC/fix_rhok.cpp
index c0976f7c43..e63ba88b93 100644
--- a/src/USER-MISC/fix_rhok.cpp
+++ b/src/USER-MISC/fix_rhok.cpp
@@ -36,7 +36,7 @@ static const char cite_fix_rhok[] =
   "title = {Direct calculation of the solid-liquid Gibbs free energy difference in a single equilibrium simulation},\n"
   "volume = {139},\n"
   "number = {10},\n"
-  "url = {http://aip.scitation.org/doi/10.1063/1.4818747},\n"
+  "url = {https://aip.scitation.org/doi/10.1063/1.4818747},\n"
   "doi = {10.1063/1.4818747},\n"
   "urldate = {2017-10-03},\n"
   "journal = {J. Chem. Phys.},\n"
diff --git a/src/USER-OMP/reaxc_bond_orders_omp.cpp b/src/USER-OMP/reaxc_bond_orders_omp.cpp
index 85a77370fa..6253df7fe7 100644
--- a/src/USER-OMP/reaxc_bond_orders_omp.cpp
+++ b/src/USER-OMP/reaxc_bond_orders_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_bond_orders_omp.h"
diff --git a/src/USER-OMP/reaxc_bonds_omp.cpp b/src/USER-OMP/reaxc_bonds_omp.cpp
index bcef3a3c87..413d50d0f9 100644
--- a/src/USER-OMP/reaxc_bonds_omp.cpp
+++ b/src/USER-OMP/reaxc_bonds_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_bonds_omp.h"
diff --git a/src/USER-OMP/reaxc_forces_omp.cpp b/src/USER-OMP/reaxc_forces_omp.cpp
index ad474a1cc8..849c239ed0 100644
--- a/src/USER-OMP/reaxc_forces_omp.cpp
+++ b/src/USER-OMP/reaxc_forces_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_forces_omp.h"
diff --git a/src/USER-OMP/reaxc_hydrogen_bonds_omp.cpp b/src/USER-OMP/reaxc_hydrogen_bonds_omp.cpp
index 029062470d..6150a6e82c 100644
--- a/src/USER-OMP/reaxc_hydrogen_bonds_omp.cpp
+++ b/src/USER-OMP/reaxc_hydrogen_bonds_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_hydrogen_bonds_omp.h"
diff --git a/src/USER-OMP/reaxc_init_md_omp.cpp b/src/USER-OMP/reaxc_init_md_omp.cpp
index fd216844eb..af982443cb 100644
--- a/src/USER-OMP/reaxc_init_md_omp.cpp
+++ b/src/USER-OMP/reaxc_init_md_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_init_md_omp.h"
diff --git a/src/USER-OMP/reaxc_multi_body_omp.cpp b/src/USER-OMP/reaxc_multi_body_omp.cpp
index 57c056fff7..86ba98631a 100644
--- a/src/USER-OMP/reaxc_multi_body_omp.cpp
+++ b/src/USER-OMP/reaxc_multi_body_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_multi_body_omp.h"
diff --git a/src/USER-OMP/reaxc_nonbonded_omp.cpp b/src/USER-OMP/reaxc_nonbonded_omp.cpp
index 3c3ca12575..301dbe8479 100644
--- a/src/USER-OMP/reaxc_nonbonded_omp.cpp
+++ b/src/USER-OMP/reaxc_nonbonded_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "pair_reaxc_omp.h"
diff --git a/src/USER-OMP/reaxc_torsion_angles_omp.cpp b/src/USER-OMP/reaxc_torsion_angles_omp.cpp
index 7d567b259c..2b9afae341 100644
--- a/src/USER-OMP/reaxc_torsion_angles_omp.cpp
+++ b/src/USER-OMP/reaxc_torsion_angles_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_torsion_angles_omp.h"
diff --git a/src/USER-OMP/reaxc_valence_angles_omp.cpp b/src/USER-OMP/reaxc_valence_angles_omp.cpp
index f9117d3a53..c42b97958f 100644
--- a/src/USER-OMP/reaxc_valence_angles_omp.cpp
+++ b/src/USER-OMP/reaxc_valence_angles_omp.cpp
@@ -23,7 +23,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_valence_angles_omp.h"
diff --git a/src/USER-REAXC/reaxc_allocate.cpp b/src/USER-REAXC/reaxc_allocate.cpp
index 0390769b53..8e7c8b2b23 100644
--- a/src/USER-REAXC/reaxc_allocate.cpp
+++ b/src/USER-REAXC/reaxc_allocate.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_allocate.h"
diff --git a/src/USER-REAXC/reaxc_bond_orders.cpp b/src/USER-REAXC/reaxc_bond_orders.cpp
index 869e796661..afa6c0ba5e 100644
--- a/src/USER-REAXC/reaxc_bond_orders.cpp
+++ b/src/USER-REAXC/reaxc_bond_orders.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_bond_orders.h"
diff --git a/src/USER-REAXC/reaxc_bonds.cpp b/src/USER-REAXC/reaxc_bonds.cpp
index 4cfd2a3c3a..dd5b8ad89e 100644
--- a/src/USER-REAXC/reaxc_bonds.cpp
+++ b/src/USER-REAXC/reaxc_bonds.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_bonds.h"
diff --git a/src/USER-REAXC/reaxc_control.cpp b/src/USER-REAXC/reaxc_control.cpp
index 1c8c24c315..b805e46bf9 100644
--- a/src/USER-REAXC/reaxc_control.cpp
+++ b/src/USER-REAXC/reaxc_control.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_control.h"
diff --git a/src/USER-REAXC/reaxc_ffield.cpp b/src/USER-REAXC/reaxc_ffield.cpp
index b865b48ad3..e4826e78c3 100644
--- a/src/USER-REAXC/reaxc_ffield.cpp
+++ b/src/USER-REAXC/reaxc_ffield.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_ffield.h"
diff --git a/src/USER-REAXC/reaxc_forces.cpp b/src/USER-REAXC/reaxc_forces.cpp
index 91f1ed55f4..2ebffed25e 100644
--- a/src/USER-REAXC/reaxc_forces.cpp
+++ b/src/USER-REAXC/reaxc_forces.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_forces.h"
diff --git a/src/USER-REAXC/reaxc_hydrogen_bonds.cpp b/src/USER-REAXC/reaxc_hydrogen_bonds.cpp
index 5929703bad..780b5f04a4 100644
--- a/src/USER-REAXC/reaxc_hydrogen_bonds.cpp
+++ b/src/USER-REAXC/reaxc_hydrogen_bonds.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_hydrogen_bonds.h"
diff --git a/src/USER-REAXC/reaxc_init_md.cpp b/src/USER-REAXC/reaxc_init_md.cpp
index 66585dad4a..e651f272ac 100644
--- a/src/USER-REAXC/reaxc_init_md.cpp
+++ b/src/USER-REAXC/reaxc_init_md.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_init_md.h"
diff --git a/src/USER-REAXC/reaxc_io_tools.cpp b/src/USER-REAXC/reaxc_io_tools.cpp
index 866e3c9891..3e1c00307d 100644
--- a/src/USER-REAXC/reaxc_io_tools.cpp
+++ b/src/USER-REAXC/reaxc_io_tools.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_io_tools.h"
diff --git a/src/USER-REAXC/reaxc_list.cpp b/src/USER-REAXC/reaxc_list.cpp
index ea59b84ff9..ff5cf98900 100644
--- a/src/USER-REAXC/reaxc_list.cpp
+++ b/src/USER-REAXC/reaxc_list.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_list.h"
diff --git a/src/USER-REAXC/reaxc_lookup.cpp b/src/USER-REAXC/reaxc_lookup.cpp
index 5ca4a30b8c..e39412ace6 100644
--- a/src/USER-REAXC/reaxc_lookup.cpp
+++ b/src/USER-REAXC/reaxc_lookup.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_lookup.h"
diff --git a/src/USER-REAXC/reaxc_multi_body.cpp b/src/USER-REAXC/reaxc_multi_body.cpp
index ed1a3d5ac1..00c8fbab2d 100644
--- a/src/USER-REAXC/reaxc_multi_body.cpp
+++ b/src/USER-REAXC/reaxc_multi_body.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_multi_body.h"
diff --git a/src/USER-REAXC/reaxc_nonbonded.cpp b/src/USER-REAXC/reaxc_nonbonded.cpp
index 497a1a0ebe..ccb8f0fed0 100644
--- a/src/USER-REAXC/reaxc_nonbonded.cpp
+++ b/src/USER-REAXC/reaxc_nonbonded.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_nonbonded.h"
diff --git a/src/USER-REAXC/reaxc_reset_tools.cpp b/src/USER-REAXC/reaxc_reset_tools.cpp
index 91b1a9e14f..e400f38970 100644
--- a/src/USER-REAXC/reaxc_reset_tools.cpp
+++ b/src/USER-REAXC/reaxc_reset_tools.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_reset_tools.h"
diff --git a/src/USER-REAXC/reaxc_system_props.cpp b/src/USER-REAXC/reaxc_system_props.cpp
index 166f070be6..e2cd7215aa 100644
--- a/src/USER-REAXC/reaxc_system_props.cpp
+++ b/src/USER-REAXC/reaxc_system_props.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_system_props.h"
diff --git a/src/USER-REAXC/reaxc_tool_box.cpp b/src/USER-REAXC/reaxc_tool_box.cpp
index b78b00568d..b27a1635fe 100644
--- a/src/USER-REAXC/reaxc_tool_box.cpp
+++ b/src/USER-REAXC/reaxc_tool_box.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_tool_box.h"
diff --git a/src/USER-REAXC/reaxc_torsion_angles.cpp b/src/USER-REAXC/reaxc_torsion_angles.cpp
index ce944b217f..380fbf4a02 100644
--- a/src/USER-REAXC/reaxc_torsion_angles.cpp
+++ b/src/USER-REAXC/reaxc_torsion_angles.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_torsion_angles.h"
diff --git a/src/USER-REAXC/reaxc_traj.cpp b/src/USER-REAXC/reaxc_traj.cpp
index 698715de22..b71d883c7d 100644
--- a/src/USER-REAXC/reaxc_traj.cpp
+++ b/src/USER-REAXC/reaxc_traj.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_traj.h"
diff --git a/src/USER-REAXC/reaxc_valence_angles.cpp b/src/USER-REAXC/reaxc_valence_angles.cpp
index 560955fa9d..14c57773c7 100644
--- a/src/USER-REAXC/reaxc_valence_angles.cpp
+++ b/src/USER-REAXC/reaxc_valence_angles.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_valence_angles.h"
diff --git a/src/USER-REAXC/reaxc_vector.cpp b/src/USER-REAXC/reaxc_vector.cpp
index 207d745df3..edee65d637 100644
--- a/src/USER-REAXC/reaxc_vector.cpp
+++ b/src/USER-REAXC/reaxc_vector.cpp
@@ -21,7 +21,7 @@
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   See the GNU General Public License for more details:
-  <http://www.gnu.org/licenses/>.
+  <https://www.gnu.org/licenses/>.
   ----------------------------------------------------------------------*/
 
 #include "reaxc_vector.h"
diff --git a/src/USER-SMTBQ/pair_smtbq.cpp b/src/USER-SMTBQ/pair_smtbq.cpp
index db292a675e..94647cb552 100644
--- a/src/USER-SMTBQ/pair_smtbq.cpp
+++ b/src/USER-SMTBQ/pair_smtbq.cpp
@@ -35,7 +35,7 @@
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See the GNU General Public License for more details:
-   <http://www.gnu.org/licenses/>.
+   <https://www.gnu.org/licenses/>.
    ------------------------------------------------------------------------- */
 
 #include "pair_smtbq.h"
diff --git a/src/hashlittle.cpp b/src/hashlittle.cpp
index 5c336c2082..5a8869bfea 100644
--- a/src/hashlittle.cpp
+++ b/src/hashlittle.cpp
@@ -51,7 +51,7 @@ satisfy this are
    14  9  3  7 17  3
 Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
 for "differ" defined as + with a one-bit base and a two-bit delta.  I
-used http://burtleburtle.net/bob/hash/avalanche.html to choose
+used https://burtleburtle.net/bob/hash/avalanche.html to choose
 the operations, constants, and arrangements of the variables.
 
 This does not achieve avalanche.  There are input bits of (a,b,c)