diff --git a/Cargo.toml b/Cargo.toml
index e02cca73..834c4e29 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,11 +19,11 @@ categories = ["no-std", "embedded", "wasm", "parser-implementations"]
 smallvec = { version = "1.6", default-features = false, features = ["union"] }
 ahash = { version = "0.7", default-features = false }
 num-traits = { version = "0.2", default-features = false }
-smartstring = { version = "0.2.7", default-features = false }
+smartstring = { version = "0.2.6", default-features = false }
 rhai_codegen = { version = ">=0.4.0", path = "codegen", default-features = false }
 
 [features]
-default = ["ahash/std", "num-traits/std", "smartstring/std"]
+default = ["smartstring/std", "ahash/std", "num-traits/std"] # remove 'smartstring/std' when smartstring is updated to support no-std
 unchecked = []                  # unchecked arithmetic
 sync = []                       # restrict to only types that implement Send + Sync
 no_position = []                # do not track position in the parser
diff --git a/no_std/no_std_test/Cargo.toml b/no_std/no_std_test/Cargo.toml
index 0aa875f2..6a85b79d 100644
--- a/no_std/no_std_test/Cargo.toml
+++ b/no_std/no_std_test/Cargo.toml
@@ -23,6 +23,16 @@ opt-level = "z"             # optimize for size
 debug = false
 rpath = false
 debug-assertions = false
-panic = "abort"
 codegen-units = 1
+panic = "abort"
+
+[profile.unix]
+inherits = "release"
 lto = true
+
+[profile.windows]
+inherits = "release"
+
+[profile.macos]
+inherits = "release"
+lto = "fat"
diff --git a/no_std/no_std_test/README.md b/no_std/no_std_test/README.md
index 5e33d4a5..1c89b11f 100644
--- a/no_std/no_std_test/README.md
+++ b/no_std/no_std_test/README.md
@@ -12,7 +12,7 @@ To Compile
 The nightly compiler is required:
 
 ```bash
-cargo +nightly build --release
+cargo +nightly build --profile unix -Z unstable-options
 ```
 
 Available profiles are: `unix`, `windows` and `macos`.