diff --git a/delorean_tsm/src/encoders/string.rs b/delorean_tsm/src/encoders/string.rs
index fd86321704..3466f06e42 100644
--- a/delorean_tsm/src/encoders/string.rs
+++ b/delorean_tsm/src/encoders/string.rs
@@ -166,6 +166,15 @@ mod tests {
         assert_eq!(dst, vec![16, 4, 12, 3, 226, 152, 131]);
     }
 
+    #[test]
+    fn encode_invalid_utf8() {
+        let src = vec![&[b'\xC0'][..]];
+        let mut dst = vec![];
+
+        encode(&src, &mut dst).expect("failed to encode src");
+        assert_eq!(dst, vec![16, 2, 4, 1, 192]);
+    }
+
     #[test]
     fn decode_no_values() {
         let src: Vec<u8> = vec![];
@@ -224,4 +233,13 @@ mod tests {
             .collect();
         assert_eq!(dst_as_strings, vec!["☃"]);
     }
+
+    #[test]
+    fn decode_invalid_utf8() {
+        let src = vec![16, 2, 4, 1, 192];
+        let mut dst = vec![];
+
+        decode(&src, &mut dst).expect("failed to decode src");
+        assert_eq!(dst, vec![&[b'\xC0'][..]]);
+    }
 }