diff --git a/src/build.rs b/src/build.rs
index 3838a86..a4df2e9 100644
--- a/src/build.rs
+++ b/src/build.rs
@@ -2,7 +2,6 @@ use std::{
     fmt::{Debug, Display},
     num::NonZeroUsize,
     path::Path,
-    process::Output,
     time::{Duration, Instant, SystemTime},
 };
 
@@ -234,9 +233,14 @@ async fn build_single_target(db: &Db, nightly: &str, target: &str, mode: BuildMo
 
     let start_time = Instant::now();
 
-    let result = build_target(tmpdir.path(), &Toolchain::from_nightly(nightly), target)
-        .await
-        .wrap_err("running build")?;
+    let result = build_target(
+        tmpdir.path(),
+        &Toolchain::from_nightly(nightly),
+        target,
+        mode,
+    )
+    .await
+    .wrap_err("running build")?;
 
     db.insert(FullBuildInfo {
         nightly: nightly.into(),
@@ -268,19 +272,16 @@ struct BuildResult {
 }
 
 /// Build a target core in a temporary directory and see whether it passes or not.
-async fn build_target(tmpdir: &Path, toolchain: &Toolchain, target: &str) -> Result<BuildResult> {
+async fn build_target(
+    tmpdir: &Path,
+    toolchain: &Toolchain,
+    target: &str,
+    mode: BuildMode,
+) -> Result<BuildResult> {
     let mut rustflags = None;
 
     let init = Command::new("cargo")
-        .arg(format!("+{toolchain}"))
-        .args([
-            "init",
-            "--lib",
-            "--name",
-            "target-test",
-            "--edition",
-            "2015",
-        ])
+        .args(["init", "--lib", "--name", "target-test"])
         .current_dir(tmpdir)
         .output()
         .await
@@ -293,58 +294,51 @@ async fn build_target(tmpdir: &Path, toolchain: &Toolchain, target: &str) -> Res
     std::fs::write(&librs, "#![no_std]\n")
         .wrap_err_with(|| format!("writing to {}", librs.display()))?;
 
-    async fn run(
-        toolchain: &Toolchain,
-        target: &str,
-        rustflags: &mut Option<String>,
-        tmpdir: &Path,
-        build_std: &str,
-    ) -> Result<Output> {
-        let mut cmd = Command::new("cargo");
-        cmd.arg(format!("+{toolchain}"))
-            .args(["build", "--release", "-j1"])
-            .arg(build_std)
-            .args(["--target", target]);
+    let mut cmd = Command::new("cargo");
 
-        let extra_flags = CUSTOM_CORE_FLAGS
-            .iter()
-            .find(|flags| flags.target == target);
+    match mode {
+        BuildMode::Core => {
+            cmd.arg(format!("+{toolchain}"))
+                .args(["build", "-Zbuild-std=core", "--release"])
+                .args(["--target", target]);
 
-        if let Some(extra_flags) = extra_flags {
-            let flags = extra_flags.flags.join(" ");
-            cmd.env("RUSTFLAGS", &flags);
-            *rustflags = Some(flags);
+            let extra_flags = CUSTOM_CORE_FLAGS
+                .iter()
+                .find(|flags| flags.target == target);
+
+            if let Some(extra_flags) = extra_flags {
+                let flags = extra_flags.flags.join(" ");
+                cmd.env("RUSTFLAGS", &flags);
+                rustflags = Some(flags);
+            }
         }
+        BuildMode::Std => {
+            cmd.arg(format!("+{toolchain}"))
+                .args(["build", "-Zbuild-std", "--release"])
+                .args(["--target", target]);
 
-        cmd.current_dir(tmpdir)
-            .output()
-            .await
-            .wrap_err("spawning cargo build")
-    }
+            let extra_flags = CUSTOM_CORE_FLAGS
+                .iter()
+                .find(|flags| flags.target == target);
 
-    let mut output = run(&toolchain, target, &mut rustflags, tmpdir, "-Zbuild-std").await?;
-    let mut stderr = String::from_utf8(output.stderr).wrap_err("cargo stderr utf8")?;
+            if let Some(extra_flags) = extra_flags {
+                let flags = extra_flags.flags.join(" ");
+                cmd.env("RUSTFLAGS", &flags);
+                rustflags = Some(flags);
+            }
+        }
+    };
+
+    let output = cmd
+        .current_dir(tmpdir)
+        .output()
+        .await
+        .wrap_err("spawning cargo build")?;
+
+    let stderr = String::from_utf8(output.stderr).wrap_err("cargo stderr utf8")?;
 
     let status = if output.status.success() {
         Status::Pass
-    // older cargo (before 2024-12-15) is clueless about std support
-    } else if stderr.contains("building std is not supported") {
-        info!("Retrying build because std is not supported");
-        output = run(
-            &toolchain,
-            target,
-            &mut rustflags,
-            tmpdir,
-            "-Zbuild-std=core",
-        )
-        .await?;
-        stderr = String::from_utf8(output.stderr).wrap_err("cargo stderr utf8")?;
-
-        if output.status.success() {
-            Status::Pass
-        } else {
-            Status::Error
-        }
     } else {
         Status::Error
     };