diff --git a/src/comp/driver/driver.rs b/src/comp/driver/driver.rs
index 03544c3d5fc8..0fa471421fc2 100644
--- a/src/comp/driver/driver.rs
+++ b/src/comp/driver/driver.rs
@@ -316,14 +316,16 @@ fn get_arch(triple: str) -> option<session::arch> {
         } else { none };
 }
 
-fn build_target_config(sopts: @session::options) -> @session::config {
+fn build_target_config(sopts: @session::options,
+                       demitter: diagnostic::emitter) -> @session::config {
     let os = alt get_os(sopts.target_triple) {
       some(os) { os }
-      none. { early_error("Unknown operating system!") }
+      none. { early_error(demitter, "Unknown operating system!") }
     };
     let arch = alt get_arch(sopts.target_triple) {
       some(arch) { arch }
-      none. { early_error("Unknown architecture! " + sopts.target_triple) }
+      none. { early_error(demitter,
+                          "Unknown architecture! " + sopts.target_triple) }
     };
     let (int_type, uint_type, float_type) = alt arch {
       session::arch_x86. {(ast::ty_i32, ast::ty_u32, ast::ty_f64)}
@@ -353,8 +355,8 @@ fn host_triple() -> str {
     ret ht != "" ? ht : fail "rustc built without CFG_HOST_TRIPLE";
 }
 
-fn build_session_options(match: getopts::match)
-   -> @session::options {
+fn build_session_options(match: getopts::match,
+                         demitter: diagnostic::emitter) -> @session::options {
     let crate_type = if opt_present(match, "lib") {
         session::lib_crate
     } else if opt_present(match, "bin") {
@@ -398,7 +400,7 @@ fn build_session_options(match: getopts::match)
     let opt_level: uint =
         if opt_present(match, "O") {
             if opt_present(match, "opt-level") {
-                early_error("-O and --opt-level both provided");
+                early_error(demitter, "-O and --opt-level both provided");
             }
             2u
         } else if opt_present(match, "opt-level") {
@@ -408,7 +410,7 @@ fn build_session_options(match: getopts::match)
               "2" { 2u }
               "3" { 3u }
               _ {
-                early_error("optimization level needs " +
+                early_error(demitter, "optimization level needs " +
                             "to be between 0-3")
               }
             }
@@ -450,8 +452,9 @@ fn build_session_options(match: getopts::match)
     ret sopts;
 }
 
-fn build_session(sopts: @session::options, input: str) -> session::session {
-    let target_cfg = build_target_config(sopts);
+fn build_session(sopts: @session::options, input: str,
+                 demitter: diagnostic::emitter) -> session::session {
+    let target_cfg = build_target_config(sopts, demitter);
     let cstore = cstore::mk_cstore();
     let filesearch = filesearch::mk_filesearch(
         sopts.maybe_sysroot,
@@ -590,8 +593,8 @@ fn build_output_filenames(ifile: str,
           obj_filename: obj_path};
 }
 
-fn early_error(msg: str) -> ! {
-    diagnostic::emit_diagnostic(none, msg, diagnostic::fatal);
+fn early_error(emitter: diagnostic::emitter, msg: str) -> ! {
+    emitter(none, msg, diagnostic::fatal);
     fail;
 }
 
diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index b91458b946a1..e43ca9b53f3d 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -9,6 +9,8 @@ import io::writer_util;
 import option::{some, none};
 import getopts::{opt_present};
 import rustc::driver::driver::*;
+import rustc::syntax::codemap;
+import rustc::driver::diagnostic;
 
 fn version(argv0: str) {
     let vers = "unknown version";
@@ -68,11 +70,16 @@ fn main(args: [str]) {
 
     if vec::len(args) == 0u { usage(binary); ret; }
 
+    let demitter = fn@(cmsp: option<(codemap::codemap, codemap::span)>,
+                       msg: str, lvl: diagnostic::level) {
+        diagnostic::emit_diagnostic(cmsp, msg, lvl);
+    };
+
     let match =
         alt getopts::getopts(args, opts()) {
           ok(m) { m }
           err(f) {
-            early_error(getopts::fail_str(f))
+            early_error(demitter, getopts::fail_str(f))
           }
         };
     if opt_present(match, "h") || opt_present(match, "help") {
@@ -84,13 +91,13 @@ fn main(args: [str]) {
         ret;
     }
     let ifile = alt vec::len(match.free) {
-      0u { early_error("No input filename given.") }
+      0u { early_error(demitter, "No input filename given.") }
       1u { match.free[0] }
-      _ { early_error("Multiple input filenames provided.") }
+      _ { early_error(demitter, "Multiple input filenames provided.") }
     };
 
-    let sopts = build_session_options(match);
-    let sess = build_session(sopts, ifile);
+    let sopts = build_session_options(match, demitter);
+    let sess = build_session(sopts, ifile, demitter);
     let odir = getopts::opt_maybe_str(match, "out-dir");
     let ofile = getopts::opt_maybe_str(match, "o");
     let cfg = build_configuration(sess, binary, ifile);