diff --git a/src/lib.rs b/src/lib.rs
index 20ec4750..ae3b93ef 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -160,7 +160,7 @@ pub struct Options {
     ///
     /// `Some(x)` will change the file to interlacing mode `x`.
     ///
-    /// Default: `Some(None)`
+    /// Default: `Some(Interlacing::None)`
     pub interlace: Option<Interlacing>,
     /// Whether to allow transparent pixels to be altered to improve compression.
     pub optimize_alpha: bool,
diff --git a/src/main.rs b/src/main.rs
index 6b536fc0..c0c8a661 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -446,7 +446,10 @@ fn parse_opts_into_struct(
 
     opts.scale_16 = matches.get_flag("scale16");
 
-    opts.fast_evaluation = matches.get_flag("fast");
+    // The default value for fast depends on the preset - make sure we don't change when not provided
+    if matches.get_flag("fast") {
+        opts.fast_evaluation = matches.get_flag("fast");
+    }
 
     opts.backup = matches.get_flag("backup");
 
diff --git a/tests/files/interlaced_palette_8_should_be_grayscale_8.png b/tests/files/interlaced_palette_8_should_be_grayscale_8.png
index bdb188fd..17356782 100644
Binary files a/tests/files/interlaced_palette_8_should_be_grayscale_8.png and b/tests/files/interlaced_palette_8_should_be_grayscale_8.png differ
diff --git a/tests/files/palette_8_should_be_grayscale_8.png b/tests/files/palette_8_should_be_grayscale_8.png
index 6d456758..5c0330c4 100644
Binary files a/tests/files/palette_8_should_be_grayscale_8.png and b/tests/files/palette_8_should_be_grayscale_8.png differ
diff --git a/tests/flags.rs b/tests/flags.rs
index 3ad9a30f..7b69c99b 100644
--- a/tests/flags.rs
+++ b/tests/flags.rs
@@ -11,6 +11,7 @@ use std::ops::Deref;
 use std::path::Path;
 use std::path::PathBuf;
 
+const GRAYSCALE: u8 = 0;
 const RGB: u8 = 2;
 const INDEXED: u8 = 3;
 const RGBA: u8 = 6;
@@ -598,7 +599,7 @@ fn fix_errors() {
         }
     };
 
-    assert_eq!(png.raw.ihdr.color_type.png_header_code(), INDEXED);
+    assert_eq!(png.raw.ihdr.color_type.png_header_code(), GRAYSCALE);
     assert_eq!(png.raw.ihdr.bit_depth, BitDepth::Eight);
 
     // Cannot check if pixels are equal because image crate cannot read corrupt (input) PNGs
diff --git a/tests/interlaced.rs b/tests/interlaced.rs
index 7cbf8474..efcea5f1 100644
--- a/tests/interlaced.rs
+++ b/tests/interlaced.rs
@@ -15,6 +15,7 @@ fn get_opts(input: &Path) -> (OutFile, oxipng::Options) {
     let mut options = oxipng::Options {
         force: true,
         fast_evaluation: false,
+        interlace: None,
         ..Default::default()
     };
     let mut filter = IndexSet::new();