diff --git a/src/test/compiletest/util.rs b/src/test/compiletest/util.rs
index 855aeb26e99..aa6c7d5abdb 100644
--- a/src/test/compiletest/util.rs
+++ b/src/test/compiletest/util.rs
@@ -10,7 +10,9 @@ fn make_new_path(path: str) -> str {
     // Windows just uses PATH as the library search path, so we have to
     // maintain the current value while adding our own
     alt getenv(lib_path_env_var()) {
-      option::some(curr) { #fmt["%s:%s", path, curr] }
+      option::some(curr) {
+        #fmt["%s%s%s", path, path_div(), curr]
+      }
       option::none. { path }
     }
 }
@@ -24,6 +26,13 @@ fn lib_path_env_var() -> str { "DYLD_LIBRARY_PATH" }
 #[cfg(target_os = "win32")]
 fn lib_path_env_var() -> str { "PATH" }
 
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "macos")]
+fn path_div() -> str { ":" }
+
+#[cfg(target_os = "win32")]
+fn path_div() -> str { ";" }
+
 fn logv(config: config, s: str) {
     log s;
     if config.verbose { io::stdout().write_line(s); }