diff --git a/build.rs b/build.rs
index 9dacdb103..73eec2a69 100644
--- a/build.rs
+++ b/build.rs
@@ -81,6 +81,7 @@ fn detect_cfgs(target: &mut Target) {
         ("", &(|_: &Target| false) as &dyn Fn(&Target) -> bool),
         ("apple", &detect_apple),
         ("bsd", &detect_bsd),
+        ("using_cmake", &|_| option_env!("FISH_CMAKE_BINARY_DIR").is_some()),
         ("cygwin", &detect_cygwin),
         ("small_main_stack", &has_small_stack),
         // See if libc supports the thread-safe localeconv_l(3) alternative to localeconv(3).
diff --git a/cmake/Rust.cmake b/cmake/Rust.cmake
index 00ddf9055..370c2287d 100644
--- a/cmake/Rust.cmake
+++ b/cmake/Rust.cmake
@@ -31,10 +31,8 @@ list(JOIN FISH_CARGO_FEATURES_LIST , FISH_CARGO_FEATURES)
 
 # Tell Cargo where our build directory is so it can find Cargo.toml.
 set(VARS_FOR_CARGO
-    "FISH_BUILD_DIR=${CMAKE_BINARY_DIR}"
+    "FISH_CMAKE_BINARY_DIR=${CMAKE_BINARY_DIR}"
     "PREFIX=${CMAKE_INSTALL_PREFIX}"
-    # Cheesy so we can tell cmake was used to build
-    "CMAKE=1"
     "DOCDIR=${CMAKE_INSTALL_FULL_DOCDIR}"
     "DATADIR=${CMAKE_INSTALL_FULL_DATADIR}"
     "SYSCONFDIR=${CMAKE_INSTALL_FULL_SYSCONFDIR}"
diff --git a/crates/build-helper/src/lib.rs b/crates/build-helper/src/lib.rs
index df9baf1b1..ddc4df2df 100644
--- a/crates/build-helper/src/lib.rs
+++ b/crates/build-helper/src/lib.rs
@@ -29,8 +29,7 @@ fn cargo_target_dir() -> Cow<'static, Path> {
 }
 
 pub fn fish_build_dir() -> Cow<'static, Path> {
-    // This is set if using CMake.
-    option_env!("FISH_BUILD_DIR")
+    option_env!("FISH_CMAKE_BINARY_DIR")
         .map(|d| Cow::Borrowed(Path::new(d)))
         .unwrap_or(cargo_target_dir())
 }
diff --git a/src/builtins/status.rs b/src/builtins/status.rs
index ad83ac7c7..54eb7e6dc 100644
--- a/src/builtins/status.rs
+++ b/src/builtins/status.rs
@@ -579,10 +579,7 @@ pub fn status(parser: &Parser, streams: &mut IoStreams, args: &mut [&wstr]) -> B
                     let host = bytes2wcstring(env!("BUILD_HOST_TRIPLE").as_bytes());
                     let profile = bytes2wcstring(env!("BUILD_PROFILE").as_bytes());
                     streams.out.append(L!("Build system: "));
-                    let buildsystem = match option_env!("CMAKE") {
-                        Some("1") => "CMake",
-                        _ => "Cargo",
-                    };
+                    let buildsystem = if cfg!(using_cmake) { "CMake" } else { "Cargo" };
                     streams.out.appendln(bytes2wcstring(buildsystem.as_bytes()));
                     streams.out.append(L!("Version: "));
                     streams.out.appendln(version);