diff --git a/Cargo.toml b/Cargo.toml
index 57111fae..5a5f19a4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -78,7 +78,12 @@ parallel = ["rayon", "indexmap/rayon"]
 [lib]
 name = "oxipng"
 path = "src/lib.rs"
+
 [profile.dev]
 opt-level = 2
+
 [profile.release]
 lto = "thin"
+
+[profile.dev.package.bit-vec]
+opt-level = 3
diff --git a/src/reduction/bit_depth.rs b/src/reduction/bit_depth.rs
index 75ad95df..aef295cf 100644
--- a/src/reduction/bit_depth.rs
+++ b/src/reduction/bit_depth.rs
@@ -75,7 +75,6 @@ pub fn reduce_bit_depth(png: &PngImage, minimum_bits: usize) -> Option<PngImage>
 #[must_use]
 pub fn reduce_bit_depth_8_or_less(png: &PngImage, mut minimum_bits: usize) -> Option<PngImage> {
     assert!((1..8).contains(&minimum_bits));
-    let mut reduced = BitVec::with_capacity(png.data.len() * 8);
     let bit_depth: usize = png.ihdr.bit_depth.as_u8() as usize;
     if minimum_bits >= bit_depth {
         return None;
@@ -130,6 +129,7 @@ pub fn reduce_bit_depth_8_or_less(png: &PngImage, mut minimum_bits: usize) -> Op
         }
     }
 
+    let mut reduced = BitVec::with_capacity(png.data.len() * 8);
     for line in png.scan_lines() {
         reduced.extend(BitVec::from_bytes(&[line.filter]));
         let bit_vec = BitVec::from_bytes(&line.data);
diff --git a/tests/flags.rs b/tests/flags.rs
index 69d79f6a..6da0ac62 100644
--- a/tests/flags.rs
+++ b/tests/flags.rs
@@ -494,6 +494,7 @@ fn fix_errors() {
 }
 
 #[test]
+#[cfg(feature = "zopfli")]
 fn zopfli_mode() {
     let input = PathBuf::from("tests/files/zopfli_mode.png");
     let (output, mut opts) = get_opts(&input);
@@ -511,6 +512,7 @@ fn zopfli_mode() {
 }
 
 #[test]
+#[cfg(feature = "libdeflater")]
 fn libdeflater_mode() {
     let input = PathBuf::from("tests/files/zopfli_mode.png");
     let (output, mut opts) = get_opts(&input);