diff --git a/src/glyph/parse.rs b/src/glyph/parse.rs
index 90264529..42f8641c 100644
--- a/src/glyph/parse.rs
+++ b/src/glyph/parse.rs
@@ -122,6 +122,12 @@ impl<'names> GlifParser<'names> {
         }
 
         self.glyph.load_object_libs()?;
+
+        let mut seen_codepoints = HashSet::new();
+        let deduplicated_codepoints =
+            self.glyph.codepoints.iter().filter(|c| seen_codepoints.insert(**c)).cloned().collect();
+        self.glyph.codepoints = deduplicated_codepoints;
+
         Ok(self.glyph)
     }
 
diff --git a/src/glyph/serialize.rs b/src/glyph/serialize.rs
index e64de211..6e09b6ad 100644
--- a/src/glyph/serialize.rs
+++ b/src/glyph/serialize.rs
@@ -1,6 +1,9 @@
 //! Writing out .glif files
 
-use std::io::{Cursor, Write};
+use std::{
+    collections::HashSet,
+    io::{Cursor, Write},
+};
 
 use quick_xml::{
     events::{BytesEnd, BytesStart, BytesText, Event},
@@ -59,8 +62,11 @@ impl Glyph {
         start.push_attribute(("format", "2"));
         writer.write_event(Event::Start(start)).map_err(GlifWriteError::Xml)?;
 
+        let mut seen_codepoints = HashSet::new();
         for codepoint in &self.codepoints {
-            writer.write_event(char_to_event(*codepoint)).map_err(GlifWriteError::Xml)?;
+            if seen_codepoints.insert(codepoint) {
+                writer.write_event(char_to_event(*codepoint)).map_err(GlifWriteError::Xml)?;
+            }
         }
 
         // Skip serializing advance if both values are zero, infinite, subnormal, or NaN.
diff --git a/src/glyph/tests.rs b/src/glyph/tests.rs
index efa23d57..e7e1b177 100644
--- a/src/glyph/tests.rs
+++ b/src/glyph/tests.rs
@@ -868,3 +868,30 @@ fn has_component_with_base() {
     assert!(glyph.has_component_with_base("dieresis"));
     assert!(!glyph.has_component_with_base("Z"));
 }
+
+#[test]
+fn deduplicate_unicodes() {
+    let data = r#"
+<?xml version="1.0" encoding="UTF-8"?>
+<glyph name="period" format="2">
+  <unicode hex="0065"/>
+  <unicode hex="0066"/>
+  <unicode hex="0065"/>
+  <unicode hex="0067"/>
+</glyph>
+"#;
+    let mut glyph = parse_glyph(data.as_bytes()).unwrap();
+    assert_eq!(glyph.codepoints, vec!['e', 'f', 'g']);
+
+    glyph.codepoints = vec!['e', 'f', 'e', 'g'];
+    let data2 = glyph.encode_xml().unwrap();
+    let data2 = std::str::from_utf8(&data2).unwrap();
+    let data2_expected = r#"<?xml version="1.0" encoding="UTF-8"?>
+<glyph name="period" format="2">
+	<unicode hex="0065"/>
+	<unicode hex="0066"/>
+	<unicode hex="0067"/>
+</glyph>
+"#;
+    assert_eq!(data2, data2_expected);
+}