diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index b6e72175e15f..46865d10fa2a 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -397,12 +397,10 @@ fn build_session_options(match: getopts::match)
     ret sopts;
 }
 
-fn build_session(binary: str,
-                 sopts: @session::options) -> session::session {
+fn build_session(sopts: @session::options) -> session::session {
     let target_cfg = build_target_config(sopts);
     let cstore = cstore::mk_cstore();
     let filesearch = filesearch::mk_filesearch(
-        binary,
         sopts.maybe_sysroot,
         sopts.target_triple,
         sopts.addl_lib_search_paths);
@@ -456,7 +454,7 @@ fn main(args: [str]) {
         ret;
     }
     let sopts = build_session_options(match);
-    let sess = build_session(binary, sopts);
+    let sess = build_session(sopts);
     let n_inputs = vec::len::<str>(match.free);
     let output_file = getopts::opt_maybe_str(match, "o");
     if n_inputs == 0u {
@@ -537,7 +535,7 @@ mod test {
               getopts::success(m) { m }
             };
         let sessopts = build_session_options(match);
-        let sess = build_session("whatever", sessopts);
+        let sess = build_session(sessopts);
         let cfg = build_configuration(sess, "whatever", "whatever");
         assert (attr::contains_name(cfg, "test"));
     }
@@ -551,7 +549,7 @@ mod test {
               getopts::success(m) { m }
             };
         let sessopts = build_session_options(match);
-        let sess = build_session("whatever", sessopts);
+        let sess = build_session(sessopts);
         let cfg = build_configuration(sess, "whatever", "whatever");
         let test_items = attr::find_meta_items_by_name(cfg, "test");
         assert (vec::len(test_items) == 1u);
diff --git a/src/comp/util/filesearch.rs b/src/comp/util/filesearch.rs
index 9e2644a2a98f..580360b967f6 100644
--- a/src/comp/util/filesearch.rs
+++ b/src/comp/util/filesearch.rs
@@ -4,6 +4,7 @@ import std::option;
 import std::fs;
 import std::vec;
 import std::str;
+import std::os;
 import back::link;
 
 export filesearch;
@@ -26,8 +27,7 @@ type filesearch = obj {
     fn get_target_lib_file_path(file: fs::path) -> fs::path;
 };
 
-fn mk_filesearch(binary_name: fs::path,
-                 maybe_sysroot: option::t<fs::path>,
+fn mk_filesearch(maybe_sysroot: option::t<fs::path>,
                  target_triple: str,
                  addl_lib_search_paths: [fs::path]) -> filesearch {
     obj filesearch_impl(sysroot: fs::path,
@@ -48,7 +48,7 @@ fn mk_filesearch(binary_name: fs::path,
         }
     }
 
-    let sysroot = get_sysroot(maybe_sysroot, binary_name);
+    let sysroot = get_sysroot(maybe_sysroot);
     log #fmt("using sysroot = %s", sysroot);
     ret filesearch_impl(sysroot, addl_lib_search_paths, target_triple);
 }
@@ -79,16 +79,18 @@ fn make_target_lib_path(sysroot: fs::path,
     ret path;
 }
 
-fn get_default_sysroot(binary: fs::path) -> fs::path {
-    let dirname = fs::dirname(binary);
-    if str::eq(dirname, binary) { ret "../"; }
-    ret fs::connect(dirname, "../");
+fn get_default_sysroot() -> fs::path {
+    alt os::get_exe_path() {
+      option::some(p) { fs::connect(p, "../") }
+      option::none. {
+        fail "can't determine value for sysroot";
+      }
+    }
 }
 
-fn get_sysroot(maybe_sysroot: option::t<fs::path>,
-               binary: fs::path) -> fs::path {
+fn get_sysroot(maybe_sysroot: option::t<fs::path>) -> fs::path {
     alt maybe_sysroot {
       option::some(sr) { sr }
-      option::none. { get_default_sysroot(binary) }
+      option::none. { get_default_sysroot() }
     }
 }
\ No newline at end of file