diff --git a/.github/workflows/cts.yml b/.github/workflows/cts.yml
index ed7ac71cb12..ac775e9b83d 100644
--- a/.github/workflows/cts.yml
+++ b/.github/workflows/cts.yml
@@ -17,7 +17,6 @@ env:
   REPO_MSRV: "1.93"
   CARGO_INCREMENTAL: false
   CARGO_TERM_COLOR: always
-  DENO_WEBGPU_DX12_COMPILER: dynamicdxc
   RUST_BACKTRACE: full
   RUSTFLAGS: -D warnings
   RUSTDOCFLAGS: -D warnings
diff --git a/xtask/src/cts.rs b/xtask/src/cts.rs
index d93a7f2227c..41c159c6421 100644
--- a/xtask/src/cts.rs
+++ b/xtask/src/cts.rs
@@ -137,11 +137,26 @@ pub fn run_cts(
         })
         .collect::<Vec<_>>();
 
-    if running_on_backend.is_none() && (!list_files.is_empty() || tests.is_empty()) {
+    if let Some(backend) = &running_on_backend {
+        shell.set_var("DENO_WEBGPU_BACKEND", backend);
+    } else if !list_files.is_empty() || tests.is_empty() {
         log::warn!("The `--backend` option was not provided. `fails-if` conditions and external");
         log::warn!("texture support are handled correctly only when a backend is specified.");
     }
 
+    #[cfg(windows)]
+    if running_on_backend.as_ref().is_none_or(|b| b == "dx12") {
+        const DEFAULT_DX12_COMPILER: &str = "dynamicdxc";
+
+        match shell.var("DENO_WEBGPU_DX12_COMPILER") {
+            Ok(value) => log::info!("Using DENO_WEBGPU_DX12_COMPILER = {value} from environment"),
+            Err(_) => {
+                shell.set_var("DENO_WEBGPU_DX12_COMPILER", DEFAULT_DX12_COMPILER);
+                log::info!("Using default DENO_WEBGPU_DX12_COMPILER = {DEFAULT_DX12_COMPILER}");
+            }
+        }
+    }
+
     let mut default_output_filter = PrintOutputWhen::Always;
 
     if tests.is_empty() && list_files.is_empty() {