diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 9025e2e..2ff1c03 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -10,6 +10,21 @@ env:
   CARGO_TERM_COLOR: always
 
 jobs:
+  msrv:
+    name: MSRV (1.85)
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v7
+    - name: Install Rust 1.85
+      uses: dtolnay/rust-toolchain@master
+      with:
+        toolchain: 1.85.0
+    - name: Check library
+      run: |
+        cargo check --package ur --lib
+        cargo check --package ur --lib --no-default-features
+
   build:
 
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index a82ed8e..772587d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,6 +6,7 @@ license = "MIT"
 version = "0.5.0"
 authors = ["Dominik Spicher <dominikspicher@gmail.com>"]
 edition = "2024"
+rust-version = "1.85"
 repository = "https://github.com/dspicher/ur-rs/"
 [workspace]
 members = ["examples/wasm", "fuzz"]
diff --git a/src/bytewords.rs b/src/bytewords.rs
index fde9e33..2bacc14 100644
--- a/src/bytewords.rs
+++ b/src/bytewords.rs
@@ -115,7 +115,7 @@ pub fn decode(encoded: &str, style: Style) -> Result<Vec<u8>, Error> {
 }
 
 fn decode_minimal(encoded: &str) -> Result<Vec<u8>, Error> {
-    if !encoded.len().is_multiple_of(2) {
+    if encoded.len() % 2 != 0 {
         return Err(Error::InvalidLength);
     }
 
diff --git a/src/fountain.rs b/src/fountain.rs
index 6952126..7b8913d 100644
--- a/src/fountain.rs
+++ b/src/fountain.rs
@@ -140,6 +140,7 @@ impl From<minicbor::encode::Error<Infallible>> for Error {
 #[derive(Debug)]
 pub struct Encoder {
     parts: Vec<Vec<u8>>,
+    fragment_count: usize,
     message_length: usize,
     checksum: u32,
     current_sequence: usize,
@@ -177,8 +178,10 @@ impl Encoder {
         }
         let fragment_length = fragment_length(message.len(), max_fragment_length);
         let fragments = partition(message.to_vec(), fragment_length);
+        let fragment_count = fragments.len();
         Ok(Self {
             parts: fragments,
+            fragment_count,
             message_length: message.len(),
             checksum: crate::crc32().checksum(message),
             current_sequence: 0,
@@ -211,7 +214,7 @@ impl Encoder {
     /// See the [`crate::fountain`] module documentation for an example.
     pub fn next_part(&mut self) -> Part {
         self.current_sequence += 1;
-        let indexes = choose_fragments(self.current_sequence, self.parts.len(), self.checksum);
+        let indexes = choose_fragments(self.current_sequence, self.fragment_count, self.checksum);
 
         let mut mixed = alloc::vec![0; self.parts[0].len()];
         for item in indexes {
@@ -220,7 +223,7 @@ impl Encoder {
 
         Part {
             sequence: self.current_sequence,
-            sequence_count: self.parts.len(),
+            sequence_count: self.fragment_count,
             message_length: self.message_length,
             checksum: self.checksum,
             data: mixed,
@@ -238,7 +241,7 @@ impl Encoder {
     /// ```
     #[must_use]
     pub const fn fragment_count(&self) -> usize {
-        self.parts.len()
+        self.fragment_count
     }
 
     /// Returns whether all original segments have been emitted at least once.
@@ -262,7 +265,7 @@ impl Encoder {
     /// [`current_sequence`]: Encoder::current_sequence
     #[must_use]
     pub const fn complete(&self) -> bool {
-        self.current_sequence >= self.parts.len()
+        self.current_sequence >= self.fragment_count
     }
 }
 
@@ -901,12 +904,17 @@ mod tests {
 
     #[test]
     fn test_fountain_encoder_is_complete() {
+        const fn progress(encoder: &Encoder) -> (usize, bool) {
+            (encoder.fragment_count(), encoder.complete())
+        }
+
         let message = crate::xoshiro::test_utils::make_message("Wolf", 256);
         let mut encoder = Encoder::new(&message, 30).unwrap();
-        for _ in 0..encoder.parts.len() {
+        assert_eq!(progress(&encoder), (9, false));
+        for _ in 0..encoder.fragment_count() {
             encoder.next_part();
         }
-        assert!(encoder.complete());
+        assert_eq!(progress(&encoder), (9, true));
     }
 
     #[test]
diff --git a/src/ur.rs b/src/ur.rs
index d352c20..174b38b 100644
--- a/src/ur.rs
+++ b/src/ur.rs
@@ -430,6 +430,10 @@ mod tests {
 
     #[test]
     fn test_ur_encoder() {
+        const fn fragment_count(encoder: &Encoder<'_>) -> usize {
+            encoder.fragment_count()
+        }
+
         let ur = make_message_ur(256, "Wolf");
         let mut encoder = Encoder::bytes(&ur, 30).unwrap();
         let expected = vec![
@@ -454,7 +458,7 @@ mod tests {
             "ur:bytes/19-9/lpbwascfadaxcywenbpljkhdcadekicpaajootjzpsdrbalpeywllbdsnbinaerkurspbncxgslgftvtsrjtksplcpeo",
             "ur:bytes/20-9/lpbbascfadaxcywenbpljkhdcayapmrleeleaxpasfrtrdkncffwjyjzgyetdmlewtkpktgllepfrltataztksmhkbot",
         ];
-        assert_eq!(encoder.fragment_count(), 9);
+        assert_eq!(fragment_count(&encoder), 9);
         for (index, e) in expected.into_iter().enumerate() {
             assert_eq!(encoder.current_index(), index);
             assert_eq!(encoder.next_part().unwrap(), e);