diff --git a/evcouplings/compare/pdb.py b/evcouplings/compare/pdb.py
index c76ba25..53f6181 100644
--- a/evcouplings/compare/pdb.py
+++ b/evcouplings/compare/pdb.py
@@ -422,9 +422,9 @@ def _get_range(object_counts):
             """
             Extract index ranges for chains, residues and atoms
             """
-            last_element = np.cumsum(object_counts, dtype=int)
+            last_element = np.cumsum(object_counts, dtype=np.int64)
             first_element = np.concatenate(
-                (np.zeros(1, dtype=int), last_element[:-1])
+                (np.zeros(1, dtype=np.int64), last_element[:-1])
             )
 
             return first_element, last_element
@@ -576,7 +576,7 @@ def get_chain(self, chain, model=0):
         )
 
         # indices of chains that match chain name, in current model
-        indices = np.arange(first_chain_index, last_chain_index, dtype=int)
+        indices = np.arange(first_chain_index, last_chain_index, dtype=np.int64)
         target_chain_indeces = indices[chain_names == chain]
 
         if len(target_chain_indeces) == 0:
@@ -598,7 +598,7 @@ def get_chain(self, chain, model=0):
         chain_indeces = np.concatenate([
             np.full(
                 self.last_residue_index[i] - self.first_residue_index[i],
-                i, dtype=int
+                i, dtype=np.int64
             ) for i in target_chain_indeces
         ])
 
diff --git a/evcouplings/couplings/model.py b/evcouplings/couplings/model.py
index e897710..fed15ff 100755
--- a/evcouplings/couplings/model.py
+++ b/evcouplings/couplings/model.py
@@ -609,7 +609,7 @@ def convert_sequences(self, sequences):
                 )
             )
 
-        S = np.empty((len(sequences), L_seq), dtype=int)
+        S = np.empty((len(sequences), L_seq), dtype=np.int64)
 
         try:
             for i, s in enumerate(sequences):
@@ -689,8 +689,8 @@ def delta_hamiltonian(self, substitutions, verify_mutants=True):
             2) delta J_ij, 3) delta h_i
 
         """
-        pos = np.empty(len(substitutions), dtype=int)
-        subs = np.empty(len(substitutions), dtype=int)
+        pos = np.empty(len(substitutions), dtype=np.int64)
+        subs = np.empty(len(substitutions), dtype=np.int64)
 
         try:
             for i, (subs_pos, subs_from, subs_to) in enumerate(substitutions):