Index: slepc/config/configure.py
===================================================================
--- slepc.orig/config/configure.py	2025-11-22 13:00:36.959396817 +0100
+++ slepc/config/configure.py	2025-11-22 13:02:25.919511427 +0100
@@ -120,7 +120,10 @@
 
 if not showhelp:
   # Create directories for configuration files
-  archdir, archdirexisted = slepc.CreateDirTest(slepc.dir,petsc.archname)
+  pseudoarch = petsc.archname
+  if slepc.buildsuffix:
+    pseudoarch += '-' + slepc.buildsuffix
+  archdir, archdirexisted = slepc.CreateDirTest(slepc.dir,pseudoarch)
   libdir  = slepc.CreateDir(archdir,'lib')
   confdir = slepc.CreateDirTwo(libdir,'slepc','conf')
 
@@ -261,7 +264,7 @@
   # run generatefortranbindings.py
   try:
     from utils import generatefortranbindings
-    generatefortranbindings.main(petsc.dir,slepc.dir,petsc.archname)
+    generatefortranbindings.main(petsc.dir,slepc.dir,pseudoarch)
   except RuntimeError as e:
     log.Exit('Unable to generate Fortran bindings:\n'+str(e))
 
@@ -318,10 +321,10 @@
 # Write reconfigure file
 if not slepc.isinstall:
   log.write('Reconfigure file in '+confdir)
-  with slepc.CreateFile(confdir,'reconfigure-'+petsc.archname+'.py') as reconfig:
+  with slepc.CreateFile(confdir,'reconfigure-'+pseudoarch+'.py') as reconfig:
     WriteReconfigScript(reconfig,slepc.dir,argdb.UsedArgs())
   try:
-    os.chmod(os.path.join(confdir,'reconfigure-'+petsc.archname+'.py'),0o775)
+    os.chmod(os.path.join(confdir,'reconfigure-'+pseudoarch+'.py'),0o775)
   except OSError as e:
     log.Exit('Unable to make reconfigure script executable:\n'+str(e))
 
Index: slepc/config/packages/slepc.py
===================================================================
--- slepc.orig/config/packages/slepc.py	2025-11-22 13:00:36.959396817 +0100
+++ slepc/config/packages/slepc.py	2025-11-22 13:00:36.954673645 +0100
@@ -28,10 +28,12 @@
     print('  --with-packages-build-dir=<dir>'.ljust(wd)+': Location to unpack and run the build process for downloaded packages')
     print('\nSLEPc:')
     print('  --prefix=<dir>'.ljust(wd)+': Specify location to install SLEPc (e.g., /usr/local)')
+    print('  --build-suffix=<string>   : Extension to name of build directory (e.g. "64" to distinguish 64-bit builds)')
     print('  --DATAFILESPATH=<dir>'.ljust(wd)+': Location of datafiles (available at https://gitlab.com/slepc/datafiles)')
 
   def ProcessArgs(self,argdb):
     self.clean       = argdb.PopBool('with-clean')[0]
+    self.buildsuffix = argdb.PopString('build-suffix')[0]
     self.force       = argdb.PopBool('force')[0]
     self.datadir     = argdb.PopPath('DATAFILESPATH',exist=True)[0]
     self.downloaddir = argdb.PopPath('with-packages-download-dir',exist=True)[0]