diff --git a/.github/workflows/R-CMD-check-wsl.yaml b/.github/workflows/R-CMD-check-wsl.yaml
index 2d6475c3f..699958a91 100644
--- a/.github/workflows/R-CMD-check-wsl.yaml
+++ b/.github/workflows/R-CMD-check-wsl.yaml
@@ -30,11 +30,6 @@ jobs:
       CMDSTANR_OPENCL_TESTS: true
 
     steps:
-      - name: cmdstan env vars
-        run: |
-          echo "CMDSTAN_PATH=${HOME}/.cmdstan" >> $GITHUB_ENV
-        shell: bash
-
       - uses: actions/checkout@v6
 
       - uses: r-lib/actions/setup-r@v2
@@ -44,7 +39,7 @@ jobs:
         with:
           extra-packages: any::rcmdcheck, local::.
 
-      - uses: Vampire/setup-wsl@v6
+      - uses: Vampire/setup-wsl@v7
         with:
             distribution: Ubuntu-22.04
             wsl-version: 2
@@ -55,12 +50,18 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install -y build-essential libopenmpi-dev ocl-icd-opencl-dev pocl-opencl-icd
+          sudo chmod 755 /root
         shell: wsl-bash {0}
 
       - name: Install cmdstan
         run: |
           cmdstanr::check_cmdstan_toolchain()
           cmdstanr::install_cmdstan(cores = 2, wsl = TRUE, overwrite = TRUE)
+          cat(
+            paste0("CMDSTAN=", cmdstanr::cmdstan_path(), "\n"),
+            file = Sys.getenv("GITHUB_ENV"),
+            append = TRUE
+          )
         shell: Rscript {0}
 
       - name: Session info
diff --git a/R/path.R b/R/path.R
index 3e4fecc15..0507d9622 100644
--- a/R/path.R
+++ b/R/path.R
@@ -9,7 +9,8 @@
 #' @export
 #'
 #' @param path (string) The full file path to the CmdStan installation. If
-#'   `NULL` (the default) then the path is set to the default path used by
+#'   `NULL` (the default) then the path is set using the `"CMDSTAN"`
+#'   environment variable when available, otherwise the default path used by
 #'   [install_cmdstan()] if it exists.
 #' @return A string. Either the file path to the CmdStan installation or the
 #'   CmdStan version number.
@@ -39,7 +40,8 @@
 #'
 set_cmdstan_path <- function(path = NULL) {
   if (is.null(path)) {
-    path <- cmdstan_default_path()
+    env_path <- Sys.getenv("CMDSTAN")
+    path <- if (nzchar(env_path)) env_path else cmdstan_default_path()
   }
   if (dir.exists(path)) {
     path <- absolute_path(path)
@@ -219,6 +221,25 @@ cmdstan_default_path <- function(dir = NULL) {
   latest_cmdstan
 }
 
+is_wsl_unc_path <- function(path) {
+  is.character(path) &&
+    length(path) == 1 &&
+    !is.na(path) &&
+    startsWith(repair_path(path), "//wsl$/")
+}
+
+cmdstan_version_from_path <- function(path) {
+  path <- repair_path(path)
+  match <- regmatches(
+    path,
+    regexpr("cmdstan-[0-9]+\\.[0-9]+\\.[0-9]+(?:-rc[0-9]+)?$", path)
+  )
+  if (!length(match) || is.na(match) || !nzchar(match)) {
+    return(NULL)
+  }
+  sub("^cmdstan-", "", match)
+}
+
 
 #' Find the version of CmdStan from makefile
 #' @noRd
@@ -226,7 +247,23 @@ cmdstan_default_path <- function(dir = NULL) {
 #' @return Version number as a string.
 read_cmdstan_version <- function(path) {
   makefile_path <- file.path(path, "makefile")
-  if (!file.exists(makefile_path)) {
+  if (is_wsl_unc_path(path)) {
+    makefile <- tryCatch(
+      suppressWarnings(readLines(makefile_path, warn = FALSE)),
+      error = function(e) NULL
+    )
+  } else if (file.exists(makefile_path)) {
+    makefile <- readLines(makefile_path)
+  } else {
+    makefile <- NULL
+  }
+  if (is.null(makefile)) {
+    if (is_wsl_unc_path(path)) {
+      version_from_path <- cmdstan_version_from_path(path)
+      if (!is.null(version_from_path)) {
+        return(version_from_path)
+      }
+    }
     warning(
       "Can't find CmdStan makefile to detect version number. ",
       "Path may not point to valid installation.",
@@ -234,7 +271,6 @@ read_cmdstan_version <- function(path) {
     )
     return(NULL)
   }
-  makefile <- readLines(makefile_path)
   version_line <- grep("^CMDSTAN_VERSION :=", makefile, value = TRUE)
   if (length(version_line) == 0) {
     stop("CmdStan makefile is missing a version number.", call. = FALSE)
diff --git a/man/set_cmdstan_path.Rd b/man/set_cmdstan_path.Rd
index b803cdd8e..fe77e09c3 100644
--- a/man/set_cmdstan_path.Rd
+++ b/man/set_cmdstan_path.Rd
@@ -14,7 +14,8 @@ cmdstan_version(error_on_NA = TRUE)
 }
 \arguments{
 \item{path}{(string) The full file path to the CmdStan installation. If
-\code{NULL} (the default) then the path is set to the default path used by
+\code{NULL} (the default) then the path is set using the \code{"CMDSTAN"}
+environment variable when available, otherwise the default path used by
 \code{\link[=install_cmdstan]{install_cmdstan()}} if it exists.}
 
 \item{error_on_NA}{(logical) Should an error be thrown if CmdStan is not
diff --git a/tests/testthat/test-install.R b/tests/testthat/test-install.R
index ccb781cc1..243b803fd 100644
--- a/tests/testthat/test-install.R
+++ b/tests/testthat/test-install.R
@@ -117,7 +117,7 @@ test_that("install_cmdstan() works with version and release_url", {
     fixed = TRUE
   )
   expect_true(dir.exists(file.path(dir, "cmdstan-2.36.0")))
-  set_cmdstan_path(cmdstan_default_path())
+  set_cmdstan_path()
 })
 
 test_that("toolchain checks on Unix work", {
@@ -143,6 +143,7 @@ test_that("toolchain checks on Unix work", {
 })
 
 test_that("clean and rebuild works", {
+  set_cmdstan_path()
   expect_output(
     rebuild_cmdstan(cores = CORES),
     paste0("CmdStan v", cmdstan_version(), " built"),
diff --git a/tests/testthat/test-path.R b/tests/testthat/test-path.R
index 5bc258191..a06af62f5 100644
--- a/tests/testthat/test-path.R
+++ b/tests/testthat/test-path.R
@@ -45,6 +45,17 @@ test_that("Setting path from env var is detected", {
   expect_false(is.null(.cmdstanr$VERSION))
 })
 
+test_that("set_cmdstan_path() uses CMDSTAN env var when path is omitted", {
+  unset_cmdstan_path()
+  withr::local_envvar(c(CMDSTAN = PATH))
+  expect_message(
+    set_cmdstan_path(),
+    paste("CmdStan path set to:", PATH),
+    fixed = TRUE
+  )
+  expect_equal(cmdstan_path(), PATH)
+})
+
 test_that("Unsupported CmdStan path from env var is rejected", {
   unset_cmdstan_path()
   .cmdstanr$WSL <- TRUE
@@ -184,6 +195,16 @@ test_that("CmdStan version helpers handle invalid inputs", {
   expect_false(is_supported_cmdstan_version("not-a-version"))
 })
 
+test_that("CmdStan version can be recovered from WSL UNC install path", {
+  wsl_path <- "//wsl$/Ubuntu-22.04/root/.cmdstan/cmdstan-2.38.0"
+
+  expect_true(is_wsl_unc_path(wsl_path))
+  expect_equal(cmdstan_version_from_path(wsl_path), "2.38.0")
+  expect_equal(cmdstan_version_from_path(paste0(wsl_path, "/")), "2.38.0")
+  expect_equal(suppressWarnings(read_cmdstan_version(wsl_path)), "2.38.0")
+  expect_null(cmdstan_version_from_path("//wsl$/Ubuntu-22.04/root/.cmdstan/not-cmdstan"))
+})
+
 test_that("cmdstan_ext() works", {
   if (os_is_windows() && !os_is_wsl()) {
     expect_identical(cmdstan_ext(), ".exe")