diff --git a/python/lammps/__init__.py b/python/lammps/__init__.py
index 48839273c5..e6ffd779a9 100644
--- a/python/lammps/__init__.py
+++ b/python/lammps/__init__.py
@@ -15,7 +15,7 @@ from .pylammps import *
 
 # convert module string version to numeric version
 def get_version_number():
-    from datetime import datetime
+    import time
     from sys import version_info
     vstring = None
     if version_info.major == 3 and version_info.minor >= 8:
@@ -32,7 +32,7 @@ def get_version_number():
     if not vstring:
         return 0
 
-    d = datetime.strptime(vstring, "%d%b%Y")
-    return d.year*10000 + d.month*100 + d.day
+    t = time.strptime(vstring, "%d%b%Y")
+    return t.tm_year*10000 + t.tm_mon*100 + t.tm_mday
 
 __version__ = get_version_number()