diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5b64511..b413d02 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,6 +37,7 @@ jobs:
         cargo build --profile=${{ matrix.profile }}
         cargo build --all-features --profile=${{ matrix.profile }}
         cargo test --profile=${{ matrix.profile }}
+        cargo test --no-default-features --features trace no_std_required --profile=${{ matrix.profile }}
   build-minimum:
     name: Build using minimum versions of dependencies
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index 6e78b25..1f7cd66 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,15 +27,21 @@ tracing infrastructure before running tests.
 """
 include = ["src/lib.rs", "LICENSE-*", "README.md", "CHANGELOG.md"]
 
+[[test]]
+name = "no_std_test"
+path = "tests/no_std_required.rs"
+required-features = ["trace"]
+
 [[test]]
 name = "default_log_filter"
 path = "tests/default_log_filter.rs"
 required-features = ["log", "unstable"]
 
 [features]
-default = ["log", "color"]
+default = ["log", "color", "std"]
+std = ["test-log-macros/std"]
 trace = ["dep:tracing-subscriber", "test-log-macros/trace"]
-log = ["dep:env_logger", "test-log-macros/log", "tracing-subscriber?/tracing-log"]
+log = ["dep:env_logger", "test-log-macros/log", "tracing-subscriber?/tracing-log", "std"]
 color = ["env_logger?/auto-color", "tracing-subscriber?/ansi"]
 # Enable unstable features. These are generally exempt from any semantic
 # versioning guarantees.
@@ -45,7 +51,7 @@ unstable = ["test-log-macros/unstable"]
 members = ["macros"]
 
 [dependencies]
-test-log-macros = {version = "0.2.15", path = "macros"}
+test-log-macros = {version = "0.2.15", default-features = false, path = "macros"}
 tracing-subscriber = {version = "0.3.17", default-features = false, optional = true, features = ["env-filter", "fmt"]}
 env_logger = {version = "0.11", default-features = false, optional = true}
 
diff --git a/macros/Cargo.toml b/macros/Cargo.toml
index 09aa829..095bbd4 100644
--- a/macros/Cargo.toml
+++ b/macros/Cargo.toml
@@ -14,6 +14,8 @@ Supporting procedural macro crate for test-log.
 proc-macro = true
 
 [features]
+default = ["std"]
+std = []
 trace = []
 log = []
 unstable = []
diff --git a/macros/src/lib.rs b/macros/src/lib.rs
index c78f9e6..2fde2ae 100644
--- a/macros/src/lib.rs
+++ b/macros/src/lib.rs
@@ -1,8 +1,15 @@
 // Copyright (C) 2019-2023 Daniel Mueller <deso@posteo.net>
 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
 extern crate proc_macro;
 
+use alloc::string::String;
+use alloc::vec;
+use alloc::vec::Vec;
+
 use proc_macro::TokenStream;
 use proc_macro2::TokenStream as Tokens;
 
@@ -199,10 +206,17 @@ fn expand_tracing_init(attribute_args: &AttributeArgs) -> Tokens {
       let __internal_event_filter = {
         use ::test_log::tracing_subscriber::fmt::format::FmtSpan;
 
-        match ::std::env::var_os("RUST_LOG_SPAN_EVENTS") {
+        #[cfg(feature = "std")]
+        let env_var = match ::std::env::var("RUST_LOG_SPAN_EVENTS") {
+            Ok(val) => Some(val),
+            Err(::std::env::VarError::NotPresent) => None,
+            Err(::std::env::VarError::NotUnicode(os_string)) => panic!("RUST_LOG_SPAN_EVENTS must be unicode compliant, found {os_string:?}"),
+        };
+        #[cfg(not(feature = "std"))]
+        let env_var = ::core::option_env!("RUST_LOG_SPAN_EVENTS");
+
+        match env_var {
           Some(mut value) => {
-            value.make_ascii_lowercase();
-            let value = value.to_str().expect("test-log: RUST_LOG_SPAN_EVENTS must be valid UTF-8");
             value
               .split(",")
               .map(|filter| match filter.trim() {
diff --git a/src/lib.rs b/src/lib.rs
index 59084b9..44b51f9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 #![deny(missing_docs)]
+#![cfg_attr(not(feature = "std"), no_std)]
 
 //! A crate providing a replacement #[[macro@test]] attribute that
 //! initializes logging and/or tracing infrastructure before running
diff --git a/tests/no_std_required.rs b/tests/no_std_required.rs
new file mode 100644
index 0000000..5aba62d
--- /dev/null
+++ b/tests/no_std_required.rs
@@ -0,0 +1,10 @@
+#![no_std]
+
+use test_log::test;
+use tracing::debug;
+
+#[test]
+fn no_std_required() {
+  debug!("It works without std!");
+  assert_eq!(1 + 1, 2);
+}