diff --git a/src/deflate/mod.rs b/src/deflate/mod.rs
index ac17577c..45e9c5fc 100644
--- a/src/deflate/mod.rs
+++ b/src/deflate/mod.rs
@@ -1,5 +1,3 @@
-use indexmap::IndexSet;
-
 mod deflater;
 pub use deflater::crc32;
 pub use deflater::deflate;
@@ -17,8 +15,8 @@ pub use zopfli_oxipng::deflate as zopfli_deflate;
 pub enum Deflaters {
     /// Use libdeflater.
     Libdeflater {
-        /// Which compression levels to try on the file (1-12)
-        compression: IndexSet<u8>,
+        /// Which compression level to use on the file (1-12)
+        compression: u8,
     },
     #[cfg(feature = "zopfli")]
     /// Use the better but slower Zopfli implementation
@@ -29,3 +27,5 @@ pub enum Deflaters {
         iterations: NonZeroU8,
     },
 }
+
+impl Copy for Deflaters {}
diff --git a/src/lib.rs b/src/lib.rs
index 899640da..b521cc77 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -47,7 +47,7 @@ pub use crate::deflate::Deflaters;
 pub use crate::error::PngError;
 pub use crate::filters::RowFilter;
 pub use crate::headers::Headers;
-pub use indexmap::{IndexMap, IndexSet};
+pub use indexmap::{indexset, IndexMap, IndexSet};
 
 mod atomicmin;
 mod colors;
@@ -232,8 +232,7 @@ impl Options {
         self.idat_recoding = false;
         self.filter.clear();
         if let Deflaters::Libdeflater { compression } = &mut self.deflate {
-            compression.clear();
-            compression.insert(5);
+            *compression = 5;
         }
         self.use_heuristics = true;
         self
@@ -242,8 +241,7 @@ impl Options {
     fn apply_preset_1(mut self) -> Self {
         self.filter.clear();
         if let Deflaters::Libdeflater { compression } = &mut self.deflate {
-            compression.clear();
-            compression.insert(10);
+            *compression = 10;
         }
         self.use_heuristics = true;
         self
@@ -263,45 +261,23 @@ impl Options {
 
     fn apply_preset_4(mut self) -> Self {
         if let Deflaters::Libdeflater { compression } = &mut self.deflate {
-            compression.clear();
-            compression.insert(12);
+            *compression = 12;
         }
         self.apply_preset_3()
     }
 
-    fn apply_preset_5(mut self) -> Self {
-        if let Deflaters::Libdeflater { compression } = &mut self.deflate {
-            compression.clear();
-            for i in 9..=12 {
-                compression.insert(i);
-            }
-        }
-        self.apply_preset_3()
+    fn apply_preset_5(self) -> Self {
+        self.apply_preset_4()
     }
 
-    fn apply_preset_6(mut self) -> Self {
-        if let Deflaters::Libdeflater { compression } = &mut self.deflate {
-            compression.clear();
-            for i in 1..=12 {
-                compression.insert(i);
-            }
-        }
-        self.apply_preset_3()
+    fn apply_preset_6(self) -> Self {
+        self.apply_preset_4()
     }
 }
 
 impl Default for Options {
     fn default() -> Options {
         // Default settings based on -o 2 from the CLI interface
-        let mut filter = IndexSet::new();
-        filter.insert(RowFilter::None);
-        filter.insert(RowFilter::MinSum);
-        let mut compression = IndexSet::new();
-        compression.insert(11);
-        // We always need NoOp to be present
-        let mut alphas = IndexSet::new();
-        alphas.insert(AlphaOptim::NoOp);
-
         Options {
             backup: false,
             check: false,
@@ -309,16 +285,16 @@ impl Default for Options {
             fix_errors: false,
             force: false,
             preserve_attrs: false,
-            filter,
+            filter: indexset! {RowFilter::None, RowFilter::MinSum},
             interlace: None,
-            alphas,
+            alphas: IndexSet::new(),
             bit_depth_reduction: true,
             color_type_reduction: true,
             palette_reduction: true,
             grayscale_reduction: true,
             idat_recoding: true,
             strip: Headers::None,
-            deflate: Deflaters::Libdeflater { compression },
+            deflate: Deflaters::Libdeflater { compression: 11 },
             use_heuristics: false,
             timeout: None,
         }
@@ -539,48 +515,20 @@ fn optimize_png(
 
     if opts.idat_recoding || reduction_occurred {
         // Go through selected permutations and determine the best
-        let combinations = if let Deflaters::Libdeflater { compression } = &opts.deflate {
-            filter.len() * compression.len()
-        } else {
-            filter.len()
-        };
-        let mut results: Vec<TrialOptions> = Vec::with_capacity(combinations);
+        let mut results: Vec<TrialOptions> = Vec::with_capacity(filter.len());
 
         for f in &filter {
-            if let Deflaters::Libdeflater { compression } = &opts.deflate {
-                for zc in compression {
-                    results.push(TrialOptions {
-                        filter: *f,
-                        compression: *zc,
-                    });
-                    if deadline.passed() {
-                        break;
-                    }
-                }
-            } else {
-                // Zopfli has no additional options.
-                results.push(TrialOptions {
-                    filter: *f,
-                    compression: 0,
-                });
-            }
-
-            if deadline.passed() {
-                break;
-            }
+            results.push(TrialOptions {
+                filter: *f,
+                compression: match opts.deflate {
+                    Deflaters::Libdeflater { compression } => compression,
+                    _ => 0,
+                },
+            });
         }
 
         info!("Trying: {} combinations", results.len());
 
-        let filters: IndexMap<RowFilter, Vec<u8>> = filter
-            .par_iter()
-            .with_max_len(1)
-            .map(|f| {
-                let png = png.clone();
-                (*f, png.raw.filter_image(*f))
-            })
-            .collect();
-
         let original_len = original_png.idat_data.len();
         let added_interlacing = opts.interlace == Some(1) && original_png.raw.ihdr.interlaced == 0;
 
@@ -590,7 +538,7 @@ fn optimize_png(
             if deadline.passed() {
                 return None;
             }
-            let filtered = &filters[&trial.filter];
+            let filtered = &png.raw.filter_image(trial.filter);
             let new_idat = match opts.deflate {
                 Deflaters::Libdeflater { .. } => {
                     deflate::deflate(filtered, trial.compression, &best_size)
diff --git a/src/main.rs b/src/main.rs
index 969b856d..5b9f41d4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -184,14 +184,11 @@ fn main() {
         )
         .arg(
             Arg::new("compression")
-                .help("zlib compression levels (1-12) - Default: 12")
+                .help("zlib compression level (1-12) - Default: 11")
                 .long("zc")
                 .takes_value(true)
-                .value_name("levels")
-                .validator(|x| match parse_numeric_range_opts(x, 1, 12) {
-                    Ok(_) => Ok(()),
-                    Err(_) => Err("Invalid option for compression".to_owned()),
-                })
+                .value_name("level")
+                .value_parser(1..=12)
                 .conflicts_with("zopfli"),
         )
         .arg(
@@ -541,8 +538,8 @@ fn parse_opts_into_struct(
             opts.deflate = Deflaters::Zopfli { iterations };
         }
     } else if let Deflaters::Libdeflater { compression } = &mut opts.deflate {
-        if let Some(x) = matches.value_of("compression") {
-            *compression = parse_numeric_range_opts(x, 1, 12).unwrap();
+        if let Some(x) = matches.get_one::<i64>("compression") {
+            *compression = *x as u8;
         }
     }