diff --git a/src/Cargo.toml b/src/Cargo.toml
index 9a53d0b7..7fa94ebe 100644
--- a/src/Cargo.toml
+++ b/src/Cargo.toml
@@ -9,17 +9,12 @@ members = [
   "szl"
 ]
 
-[profile.dev]
-panic = "abort"
-lto = false
-
 [profile.release]
 panic = "abort"
 debug = true
-# Link-Time Optimization:
-# turn off if you get unusable debug symbols.
+codegen-units = 1
+opt-level = 'z'
 lto = true
-opt-level = 'z'  # Optimize for size.
 
 [patch.crates-io]
 core_io = { path = "./libcoreio" }
diff --git a/src/szl/build.rs b/src/szl/build.rs
index a02dfd01..2fe03fc3 100644
--- a/src/szl/build.rs
+++ b/src/szl/build.rs
@@ -32,7 +32,7 @@ pub fn compile_unlzma() {
     cfg.flag("-fPIC");
     cfg.flag("-fno-stack-protector");
     cfg.flag("--target=armv7-none-eabihf");
-    cfg.flag("-O2");
+    cfg.flag("-Os");
 
     let sources = vec![
         "unlzma.c",