diff --git a/src/tools/run-make-support/src/lib.rs b/src/tools/run-make-support/src/lib.rs
index ba27e6615d7c2..820218732cecd 100644
--- a/src/tools/run-make-support/src/lib.rs
+++ b/src/tools/run-make-support/src/lib.rs
@@ -1,5 +1,5 @@
 use std::env;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::process::{Command, Output};
 
 fn setup_common_build_cmd() -> Command {
@@ -88,36 +88,36 @@ impl AuxBuildInvocationBuilder {
     }
 }
 
-fn path_sep(target: &str) -> char {
-    if target.contains("windows") { ';' } else { ':' }
-}
-
 fn run_common(bin_name: &str) -> (Command, Output) {
-    let target = std::env::var("TARGET").unwrap();
+    let target = env::var("TARGET").unwrap();
 
     let bin_name =
         if target.contains("windows") { format!("{}.exe", bin_name) } else { bin_name.to_owned() };
 
     let mut bin_path = PathBuf::new();
-    bin_path.push(std::env::var("TMPDIR").unwrap());
+    bin_path.push(env::var("TMPDIR").unwrap());
     bin_path.push(&bin_name);
-    let ld_lib_path_envvar = std::env::var("LD_LIB_PATH_ENVVAR").unwrap();
+    let ld_lib_path_envvar = env::var("LD_LIB_PATH_ENVVAR").unwrap();
     let mut cmd = Command::new(bin_path);
     cmd.env(&ld_lib_path_envvar, {
-        let mut target_rpath_env_path = String::new();
-        target_rpath_env_path.push_str(&std::env::var("TMPDIR").unwrap());
-        target_rpath_env_path.push(path_sep(&target));
-        target_rpath_env_path.push_str(&std::env::var("TARGET_RPATH_ENV").unwrap());
-        target_rpath_env_path.push(path_sep(&target));
-        target_rpath_env_path.push_str(&std::env::var(&ld_lib_path_envvar).unwrap());
-        target_rpath_env_path
+        let mut paths = vec![];
+        paths.push(PathBuf::from(env::var("TMPDIR").unwrap()));
+        for p in env::split_paths(&env::var("TARGET_RPATH_ENV").unwrap()) {
+            paths.push(p.to_path_buf());
+        }
+        for p in env::split_paths(&env::var(&ld_lib_path_envvar).unwrap()) {
+            paths.push(p.to_path_buf());
+        }
+        env::join_paths(paths.iter()).unwrap()
     });
 
     if target.contains("windows") {
-        let mut path = std::env::var("PATH").unwrap_or(String::new());
-        path.push(path_sep(&target));
-        path.push_str(&std::env::var("TARGET_RPATH_DIR").unwrap());
-        cmd.env("PATH", &path);
+        let mut paths = vec![];
+        for p in env::split_paths(&std::env::var("PATH").unwrap_or(String::new())) {
+            paths.push(p.to_path_buf());
+        }
+        paths.push(Path::new(&std::env::var("TARGET_RPATH_DIR").unwrap()).to_path_buf());
+        cmd.env("PATH", env::join_paths(paths.iter()).unwrap());
     }
 
     let output = cmd.output().unwrap();