--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@@ -1,18 +1,24 @@
 # -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+@imports(_from='os.path', _import='expanduser')
+def rustup_path(what):
+    # rustup installs rustc/cargo into ~/.cargo/bin by default,
+    # so look there if the binaries aren't in $PATH.
+    return [what, os.path.join(expanduser('~/.cargo/bin'), what)]
+
 # Rust is required by `rust_compiler` below. We allow_missing here
 # to propagate failures to the better error message there.
-rustc = check_prog('RUSTC', ['rustc'], allow_missing=True)
-cargo = check_prog('CARGO', ['cargo'], allow_missing=True)
+rustc = check_prog('RUSTC', rustup_path('rustc'), allow_missing=True)
+cargo = check_prog('CARGO', rustup_path('cargo'), allow_missing=True)
 
 @depends_if(rustc)
 @checking('rustc version', lambda info: info.version)
 def rustc_info(rustc):
     out = check_cmd_output(rustc, '--version', '--verbose').splitlines()
     info = dict((s.strip() for s in line.split(':', 1)) for line in out[1:])
     return namespace(
         version=Version(info.get('release', '0')),