diff --git a/pendulum/formatting/formatter.py b/pendulum/formatting/formatter.py
index c6ed389a..76a4db4f 100644
--- a/pendulum/formatting/formatter.py
+++ b/pendulum/formatting/formatter.py
@@ -25,8 +25,8 @@
 _MATCH_5_TO_6 = "\d{5}\d?"
 _MATCH_UNSIGNED = "\d+"
 _MATCH_SIGNED = "[+-]?\d+"
-_MATCH_OFFSET = "(?i)Z|[+-]\d\d:?\d\d"
-_MATCH_SHORT_OFFSET = "(?i)Z|[+-]\d\d(?::?\d\d)?"
+_MATCH_OFFSET = "[Zz]|[+-]\d\d:?\d\d"
+_MATCH_SHORT_OFFSET = "[Zz]|[+-]\d\d(?::?\d\d)?"
 _MATCH_TIMESTAMP = "[+-]?\d+(\.\d{1,6})?"
 _MATCH_WORD = (
     "(?i)[0-9]*"
diff --git a/tests/formatting/test_formatter.py b/tests/formatting/test_formatter.py
index 40f2ee8e..80bb4517 100644
--- a/tests/formatting/test_formatter.py
+++ b/tests/formatting/test_formatter.py
@@ -238,8 +238,8 @@ def test_date_formats():
 def test_escape():
     f = Formatter()
     d = pendulum.datetime(2016, 8, 28)
-    assert f.format(d, "[YYYY] YYYY \[YYYY\]") == "YYYY 2016 [2016]"
-    assert f.format(d, "\D D \\\D") == "D 28 \\28"
+    assert f.format(d, r"[YYYY] YYYY \[YYYY\]") == "YYYY 2016 [2016]"
+    assert f.format(d, r"\D D \\D") == "D 28 \\28"
 
 
 def test_date_formats_missing():