diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index a045801322f..1ef81eb35ed 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -551,12 +551,14 @@ fn main(args: [str]) {
     let glu: str = binary_dir + "/lib/glue.o";
     let main: str = binary_dir + "/lib/main.o";
     let stage: str = "-L" + binary_dir + "/lib";
-    let prog: str = "gcc";
+    let prog: istr = ~"gcc";
     // The invocations of gcc share some flags across platforms
 
     let gcc_args =
-        [stage, "-Lrt", "-lrustrt", glu, "-m32", "-o", saved_out_filename,
-         saved_out_filename + ".o"];
+        [istr::from_estr(stage),
+         ~"-Lrt", ~"-lrustrt", istr::from_estr(glu),
+         ~"-m32", ~"-o", istr::from_estr(saved_out_filename),
+         istr::from_estr(saved_out_filename) + ~".o"];
     let lib_cmd;
 
     let os = sess.get_targ_cfg().os;
@@ -590,46 +592,49 @@ fn main(args: [str]) {
     let cstore = sess.get_cstore();
     for cratepath: str in cstore::get_used_crate_files(cstore) {
         if str::ends_with(cratepath, ".rlib") {
-            gcc_args += [cratepath];
+            gcc_args += [istr::from_estr(cratepath)];
             cont;
         }
         let cratepath = istr::from_estr(cratepath);
         let dir = fs::dirname(cratepath);
-        if dir != ~"" { gcc_args += ["-L" + istr::to_estr(dir)]; }
+        if dir != ~"" { gcc_args += [~"-L" + dir]; }
         let libarg = unlib(sess.get_targ_cfg(), fs::basename(cratepath));
-        gcc_args += ["-l" + istr::to_estr(libarg)];
+        gcc_args += [~"-l" + libarg];
     }
 
     let ula = cstore::get_used_link_args(cstore);
-    for arg: str in ula { gcc_args += [arg]; }
+    for arg: str in ula { gcc_args += [istr::from_estr(arg)]; }
 
     let used_libs = cstore::get_used_libraries(cstore);
-    for l: str in used_libs { gcc_args += ["-l" + l]; }
+    for l: str in used_libs { gcc_args += [~"-l" + istr::from_estr(l)]; }
 
     if sopts.library {
-        gcc_args += [lib_cmd];
+        gcc_args += [istr::from_estr(lib_cmd)];
     } else {
         // FIXME: why do we hardcode -lm?
-        gcc_args += ["-lm", main];
+        gcc_args += [~"-lm", istr::from_estr(main)];
     }
     // We run 'gcc' here
 
     let err_code = run::run_program(prog, gcc_args);
     if 0 != err_code {
         sess.err(#fmt["linking with gcc failed with code %d", err_code]);
-        sess.note(#fmt["gcc arguments: %s", str::connect(gcc_args, " ")]);
+        sess.note(#fmt["gcc arguments: %s",
+                       istr::to_estr(istr::connect(gcc_args, ~" "))]);
         sess.abort_if_errors();
     }
     // Clean up on Darwin
 
     if sess.get_targ_cfg().os == session::os_macos {
-        run::run_program("dsymutil", [saved_out_filename]);
+        run::run_program(~"dsymutil",
+                         [istr::from_estr(saved_out_filename)]);
     }
 
 
     // Remove the temporary object file if we aren't saving temps
     if !sopts.save_temps {
-        run::run_program("rm", [saved_out_filename + ".o"]);
+        run::run_program(~"rm",
+                         [istr::from_estr(saved_out_filename) + ~".o"]);
     }
 }
 
diff --git a/src/fuzzer/fuzzer.rs b/src/fuzzer/fuzzer.rs
index 3f88f26bdcd..0d4a546902e 100644
--- a/src/fuzzer/fuzzer.rs
+++ b/src/fuzzer/fuzzer.rs
@@ -24,7 +24,7 @@ import rustc::syntax::print::pprust;
 fn write_file(filename: &str, content: &str) {
     io::file_writer(filename, [io::create, io::truncate]).write_str(content);
     // Work around https://github.com/graydon/rust/issues/726
-    std::run::run_program("chmod", ["644", filename]);
+    std::run::run_program(~"chmod", [~"644", istr::from_estr(filename)]);
 }
 
 fn file_contains(filename: &str, needle: &str) -> bool {
@@ -190,8 +190,9 @@ fn check_whole_compiler(code: &str) {
     let filename = "test.rs";
     write_file(filename, code);
     let p =
-        std::run::program_output("/Users/jruderman/code/rust/build/stage1/rustc",
-                                 ["-c", filename]);
+        std::run::program_output(
+            ~"/Users/jruderman/code/rust/build/stage1/rustc",
+            [~"-c", istr::from_estr(filename)]);
 
     //log_err #fmt("Status: %d", p.status);
     //log_err "Output: " + p.out;
@@ -328,9 +329,9 @@ fn check_roundtrip_convergence(code: &str, maxIters: uint) {
         log_err #fmt["Did not converge after %u iterations!", i];
         write_file("round-trip-a.rs", old);
         write_file("round-trip-b.rs", new);
-        std::run::run_program("diff",
-                              ["-w", "-u", "round-trip-a.rs",
-                               "round-trip-b.rs"]);
+        std::run::run_program(~"diff",
+                              [~"-w", ~"-u", ~"round-trip-a.rs",
+                               ~"round-trip-b.rs"]);
         fail "Mismatch";
     }
 }
diff --git a/src/lib/run_program.rs b/src/lib/run_program.rs
index fb593bca58a..4482431f67c 100644
--- a/src/lib/run_program.rs
+++ b/src/lib/run_program.rs
@@ -19,8 +19,10 @@ fn arg_vec(prog: str, args: &[str]) -> [sbuf] {
     ret argptrs;
 }
 
-fn spawn_process(prog: str, args: &[str], in_fd: int, out_fd: int,
+fn spawn_process(prog: &istr, args: &[istr], in_fd: int, out_fd: int,
                  err_fd: int) -> int {
+    let prog = istr::to_estr(prog);
+    let args = istr::to_estrs(args);
     // Note: we have to hold on to this vector reference while we hold a
     // pointer to its buffer
     let argv = arg_vec(prog, args);
@@ -29,7 +31,7 @@ fn spawn_process(prog: str, args: &[str], in_fd: int, out_fd: int,
     ret pid;
 }
 
-fn run_program(prog: str, args: &[str]) -> int {
+fn run_program(prog: &istr, args: &[istr]) -> int {
     ret os::waitpid(spawn_process(prog, args, 0, 0, 0));
 }
 
@@ -46,7 +48,7 @@ type program =
 
 resource program_res(p: program) { p.destroy(); }
 
-fn start_program(prog: str, args: &[str]) -> @program_res {
+fn start_program(prog: &istr, args: &[istr]) -> @program_res {
     let pipe_input = os::pipe();
     let pipe_output = os::pipe();
     let pipe_err = os::pipe();
@@ -106,7 +108,7 @@ fn read_all(rd: &io::reader) -> str {
     ret buf;
 }
 
-fn program_output(prog: str, args: [str]) ->
+fn program_output(prog: &istr, args: &[istr]) ->
    {status: int, out: str, err: str} {
     let pr = start_program(prog, args);
     pr.close_input();
diff --git a/src/test/compiletest/procsrv.rs b/src/test/compiletest/procsrv.rs
index 03fbb9cb1a4..140821473ad 100644
--- a/src/test/compiletest/procsrv.rs
+++ b/src/test/compiletest/procsrv.rs
@@ -13,6 +13,7 @@ import std::os;
 import std::run;
 import std::io;
 import std::str;
+import std::istr;
 import std::comm::chan;
 import std::comm::port;
 import std::comm::send;
@@ -128,7 +129,8 @@ fn worker(p: port<request>) {
         let pipe_out = os::pipe();
         let pipe_err = os::pipe();
         let spawnproc =
-            bind run::spawn_process(execparms.prog, execparms.args,
+            bind run::spawn_process(istr::from_estr(execparms.prog),
+                                    istr::from_estrs(execparms.args),
                                     pipe_in.in, pipe_out.out, pipe_err.out);
         let pid = with_lib_path(execparms.lib_path, spawnproc);
 
diff --git a/src/test/stdtest/run.rs b/src/test/stdtest/run.rs
index b60a3935500..54f33b3e057 100644
--- a/src/test/stdtest/run.rs
+++ b/src/test/stdtest/run.rs
@@ -11,9 +11,9 @@ import std::vec;
 #[cfg(target_os = "macos")]
 #[test]
 fn test_leaks() {
-    run::run_program("echo", []);
-    run::start_program("echo", []);
-    run::program_output("echo", []);
+    run::run_program(~"echo", []);
+    run::start_program(~"echo", []);
+    run::program_output(~"echo", []);
 }
 
 // FIXME
@@ -29,7 +29,8 @@ fn test_pipes() {
     let pipe_err = os::pipe();
 
     let pid =
-        run::spawn_process("cat", [], pipe_in.in, pipe_out.out, pipe_err.out);
+        run::spawn_process(~"cat", [],
+                           pipe_in.in, pipe_out.out, pipe_err.out);
     os::libc::close(pipe_in.in);
     os::libc::close(pipe_out.out);
     os::libc::close(pipe_err.out);