--- a/toolkit/crashreporter/google-breakpad/src/common/moz.build
+++ b/toolkit/crashreporter/google-breakpad/src/common/moz.build
@@ -47,17 +47,19 @@ if CONFIG['OS_ARCH'] != 'WINNT':
     if CONFIG['OS_ARCH'] == 'Darwin':
         HOST_CXXFLAGS += [
             '-stdlib=libc++',
         ]
     HOST_CXXFLAGS += [
         '-O2',
         '-g',
     ]
-    HOST_DEFINES['HAVE_RUST_DEMANGLE'] = True
+    # The tup build doesn't currently link this properly: bug 1475278
+    if 'Tup' not in CONFIG['BUILD_BACKENDS']:
+        HOST_DEFINES['HAVE_RUST_DEMANGLE'] = True
     LOCAL_INCLUDES += [
         '/toolkit/crashreporter/rust',
     ]
     HostLibrary('host_breakpad_common_s')
 
 if CONFIG['OS_TARGET'] == 'Android':
     # We don't support unifying assembly files.
     SOURCES += [