diff --git a/src/etc/generate-deriving-span-tests.py b/src/etc/generate-deriving-span-tests.py
index 15c9fc2e504a1..5b106275ac9d2 100755
--- a/src/etc/generate-deriving-span-tests.py
+++ b/src/etc/generate-deriving-span-tests.py
@@ -18,7 +18,7 @@
 sample usage: src/etc/generate-deriving-span-tests.py
 """
 
-import sys, os, datetime, stat
+import sys, os, datetime, stat, re
 
 TEST_DIR = os.path.abspath(
     os.path.join(os.path.dirname(__file__), '../test/compile-fail'))
@@ -87,16 +87,25 @@ def create_test_case(type, trait, super_traits, error_count):
 def write_file(name, string):
     test_file = os.path.join(TEST_DIR, 'derives-span-%s.rs' % name)
 
+    with open(test_file) as f:
+        old_str = f.read()
+        old_str_ignoring_date = re.sub(r'^// Copyright \d+',
+                                        '// Copyright {year}'.format(year = YEAR), old_str)
+        if old_str_ignoring_date == string:
+            # if all we're doing is updating the copyright year, ignore it
+            return 0
+
     # set write permission if file exists, so it can be changed
     if os.path.exists(test_file):
         os.chmod(test_file, stat.S_IWUSR)
 
-    with open(test_file, 'wt') as f:
+    with open(test_file, 'w') as f:
         f.write(string)
 
     # mark file read-only
     os.chmod(test_file, stat.S_IRUSR|stat.S_IRGRP|stat.S_IROTH)
 
+    return 1
 
 
 ENUM = 1
@@ -120,11 +129,15 @@ def write_file(name, string):
                               ('Hash', [], 1)]:
     traits[trait] = (ALL, supers, errs)
 
+files = 0
+
 for (trait, (types, super_traits, error_count)) in traits.items():
     mk = lambda ty: create_test_case(ty, trait, super_traits, error_count)
     if types & ENUM:
-        write_file(trait + '-enum', mk(ENUM_TUPLE))
-        write_file(trait + '-enum-struct-variant', mk(ENUM_STRUCT))
+        files += write_file(trait + '-enum', mk(ENUM_TUPLE))
+        files += write_file(trait + '-enum-struct-variant', mk(ENUM_STRUCT))
     if types & STRUCT:
-        write_file(trait + '-struct', mk(STRUCT_FIELDS))
-        write_file(trait + '-tuple-struct', mk(STRUCT_TUPLE))
+        files += write_file(trait + '-struct', mk(STRUCT_FIELDS))
+        files += write_file(trait + '-tuple-struct', mk(STRUCT_TUPLE))
+
+print('Generated {files} deriving span test{}.'.format('s' if files != 1 else '', files = files))