diff --git a/build.py b/build.py
index 2f57d8c32746c0d6338c7fbe8aa1ce7e44bdbc22..48a26d8d0cf6a8eff7ab0f8f7d2b871f85a6e95f 100644
--- a/build.py
+++ b/build.py
@@ -15,7 +15,7 @@ if __name__ == '__main__':
 
     i = 1
     while os.path.exists('src/lab%s.md' % (i, )):
-        lab_name, i = 'lab%s' % (i, ), i+1
+        lab_name = 'lab%s' % (i, )
         dist_lp, src_md, src_json = 'dist/' + lab_name+'/', 'src/' + lab_name + '.md', 'src/'+lab_name+'.json'
 
         os.system('mkdir '+dist_lp)                         # Make directories
@@ -33,3 +33,5 @@ if __name__ == '__main__':
                 labout.write(lab.encode('utf8'))
 
             os.system(('pandoc %s%s.md -s -o %s%s.pdf') % (dist_lp, ex_no, dist_lp, ex_no))
+
+        i += 1
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