diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 679c40c68a..e9865f408e 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -38,14 +38,14 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: ["1.61.0", nightly, beta]
+        rust: ["1.63.0", nightly, beta]
     steps:
     - uses: actions/checkout@v4
 
     - uses: dtolnay/rust-toolchain@nightly
-      if: ${{ matrix.rust == '1.61.0' }}
+      if: ${{ matrix.rust == '1.63.0' }}
     - name: Generate Cargo.lock with minimal-version dependencies
-      if: ${{ matrix.rust == '1.61.0' }}
+      if: ${{ matrix.rust == '1.63.0' }}
       run: cargo -Zminimal-versions generate-lockfile
 
     - uses: dtolnay/rust-toolchain@v1
@@ -58,7 +58,7 @@ jobs:
     - name: build
       run: cargo build -v --features webp,webp-encoder
     - name: test
-      if: ${{ matrix.rust != '1.61.0' }}
+      if: ${{ matrix.rust != '1.63.0' }}
       run: >
         cargo test -v --features webp,webp-encoder &&
         cargo doc -v --features webp,webp-encoder
diff --git a/Cargo.toml b/Cargo.toml
index c7cfd08393..59bfee1d2c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2021"
 resolver = "2"
 
 # note: when changed, also update test runner in `.github/workflows/rust.yml`
-rust-version = "1.61.0"
+rust-version = "1.63.0"
 
 license = "MIT OR Apache-2.0"
 description = "Imaging library. Provides basic image processing and encoders/decoders for common image formats."
diff --git a/src/codecs/png.rs b/src/codecs/png.rs
index 39e1e5cb97..d2d0bf6898 100644
--- a/src/codecs/png.rs
+++ b/src/codecs/png.rs
@@ -551,10 +551,12 @@ pub struct PngEncoder<W: Write> {
 /// Compression level of a PNG encoder. The default setting is `Fast`.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[non_exhaustive]
+#[derive(Default)]
 pub enum CompressionType {
     /// Default compression level
     Default,
     /// Fast, minimal compression
+    #[default]
     Fast,
     /// High compression level
     Best,
@@ -571,6 +573,7 @@ pub enum CompressionType {
 /// The default filter is `Adaptive`.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[non_exhaustive]
+#[derive(Default)]
 pub enum FilterType {
     /// No processing done, best used for low bit depth grayscale or data with a
     /// low color count
@@ -585,6 +588,7 @@ pub enum FilterType {
     Paeth,
     /// Uses a heuristic to select one of the preceding filters for each
     /// scanline rather than one filter for the entire image
+    #[default]
     Adaptive,
 }
 
@@ -769,18 +773,6 @@ impl ImageError {
     }
 }
 
-impl Default for CompressionType {
-    fn default() -> Self {
-        CompressionType::Fast
-    }
-}
-
-impl Default for FilterType {
-    fn default() -> Self {
-        FilterType::Adaptive
-    }
-}
-
 impl fmt::Display for BadPngRepresentation {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
diff --git a/src/codecs/pnm/decoder.rs b/src/codecs/pnm/decoder.rs
index 03faf7c084..9105662269 100644
--- a/src/codecs/pnm/decoder.rs
+++ b/src/codecs/pnm/decoder.rs
@@ -421,13 +421,6 @@ trait HeaderReader: BufRead {
         Ok(string)
     }
 
-    /// Read the next line
-    fn read_next_line(&mut self) -> ImageResult<String> {
-        let mut buffer = String::new();
-        self.read_line(&mut buffer)?;
-        Ok(buffer)
-    }
-
     fn read_next_u32(&mut self) -> ImageResult<u32> {
         let s = self.read_next_string()?;
         s.parse::<u32>()
diff --git a/src/codecs/webp/encoder.rs b/src/codecs/webp/encoder.rs
index 8fb125b65b..4f809f901e 100644
--- a/src/codecs/webp/encoder.rs
+++ b/src/codecs/webp/encoder.rs
@@ -32,6 +32,7 @@ pub struct WebPQuality(Quality);
 #[derive(Debug, Copy, Clone)]
 enum Quality {
     Lossless,
+    #[allow(unused)]
     #[deprecated = "Lossy encoding will be removed in a future version. See: https://github.com/image-rs/image/issues/1984"]
     Lossy(u8),
 }
diff --git a/src/codecs/webp/vp8.rs b/src/codecs/webp/vp8.rs
index f18b64aeb4..bebd1d1d49 100644
--- a/src/codecs/webp/vp8.rs
+++ b/src/codecs/webp/vp8.rs
@@ -50,9 +50,10 @@ const B_HU_PRED: i8 = 9;
 
 // Prediction mode enum
 #[repr(i8)]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
 enum LumaMode {
     /// Predict DC using row above and column to the left.
+    #[default]
     DC = DC_PRED,
 
     /// Predict rows using row above.
@@ -69,9 +70,10 @@ enum LumaMode {
 }
 
 #[repr(i8)]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
 enum ChromaMode {
     /// Predict DC using row above and column to the left.
+    #[default]
     DC = DC_PRED,
 
     /// Predict rows using row above.
@@ -85,8 +87,9 @@ enum ChromaMode {
 }
 
 #[repr(i8)]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
 enum IntraMode {
+    #[default]
     DC = B_DC_PRED,
     TM = B_TM_PRED,
     VE = B_VE_PRED,
@@ -2126,12 +2129,6 @@ impl LumaMode {
     }
 }
 
-impl Default for LumaMode {
-    fn default() -> Self {
-        LumaMode::DC
-    }
-}
-
 impl ChromaMode {
     fn from_i8(val: i8) -> Option<Self> {
         Some(match val {
@@ -2144,12 +2141,6 @@ impl ChromaMode {
     }
 }
 
-impl Default for ChromaMode {
-    fn default() -> Self {
-        ChromaMode::DC
-    }
-}
-
 impl IntraMode {
     fn from_i8(val: i8) -> Option<Self> {
         Some(match val {
@@ -2168,12 +2159,6 @@ impl IntraMode {
     }
 }
 
-impl Default for IntraMode {
-    fn default() -> Self {
-        IntraMode::DC
-    }
-}
-
 fn init_top_macroblocks(width: usize) -> Vec<MacroBlock> {
     let mb_width = (width + 15) / 16;