diff --git a/build_pycompat.py b/build_pycompat.py
index 7f26438..8886d21 100755
--- a/build_pycompat.py
+++ b/build_pycompat.py
@@ -81,7 +81,7 @@ tests = {
         'Thu Sep 25 10:36:28 BRST 2003', '1996.07.10 AD at 15:08:56 PDT',
         'Tuesday, April 12, 1952 AD 3:30:42pm PST',
         'November 5, 1994, 8:15:30 am EST', '1994-11-05T08:15:30-05:00',
-        '1994-11-05T08:15:30Z', '1976-07-04T00:01:02Z',
+        '1994-11-05T08:15:30Z', '1976-07-04T00:01:02Z', '1986-07-05T08:15:30z',
         'Tue Apr 4 00:22:12 PDT 1995'
     ],
     'test_fuzzy_tzinfo': [
diff --git a/src/lib.rs b/src/lib.rs
index 1289b78..0092f33 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -347,7 +347,9 @@ impl ParserInfo {
             res.year = Some(self.convertyear(y, res.century_specified))
         };
 
-        if res.tzoffset == Some(0) && res.tzname.is_none() || res.tzname == Some("Z".to_owned()) {
+        if (res.tzoffset == Some(0) && res.tzname.is_none())
+            || (res.tzname == Some("Z".to_owned()) || res.tzname == Some("z".to_owned()))
+        {
             res.tzname = Some("UTC".to_owned());
             res.tzoffset = Some(0);
         } else if res.tzoffset != Some(0)
@@ -885,7 +887,7 @@ impl Parser {
             && tzname.is_none()
             && tzoffset.is_none()
             && token.len() <= 5
-            && all_ascii_upper
+            && (all_ascii_upper || self.info.utczone.contains_key(token))
     }
 
     #[allow(clippy::unnecessary_unwrap)]
diff --git a/src/tests/pycompat_parser.rs b/src/tests/pycompat_parser.rs
index 6ad4066..444eb53 100644
--- a/src/tests/pycompat_parser.rs
+++ b/src/tests/pycompat_parser.rs
@@ -3348,6 +3348,33 @@ fn test_parse_ignoretz6() {
 
 #[test]
 fn test_parse_ignoretz7() {
+    let info = ParserInfo::default();
+    let pdt = PyDateTime {
+        year: 1986,
+        month: 7,
+        day: 5,
+        hour: 8,
+        minute: 15,
+        second: 30,
+        micros: 0,
+        tzo: None,
+    };
+    parse_and_assert(
+        pdt,
+        info,
+        "1986-07-05T08:15:30z",
+        None,
+        None,
+        false,
+        false,
+        None,
+        true,
+        &HashMap::new(),
+    );
+}
+
+#[test]
+fn test_parse_ignoretz8() {
     let info = ParserInfo::default();
     let pdt = PyDateTime {
         year: 1995,