diff --git a/src/test/run-pass/cci_iter_exe.rs b/src/test/run-pass/cci_iter_exe.rs
index 6799daf93e8..419199e1768 100644
--- a/src/test/run-pass/cci_iter_exe.rs
+++ b/src/test/run-pass/cci_iter_exe.rs
@@ -1,3 +1,4 @@
+// xfail-fast - check-fast doesn't understand aux-build
 // aux-build:cci_iter_lib.rs
 
 use std;
diff --git a/src/test/run-pass/cci_no_inline_exe.rs b/src/test/run-pass/cci_no_inline_exe.rs
index eca86bcf82c..62b4fdb9fd5 100644
--- a/src/test/run-pass/cci_no_inline_exe.rs
+++ b/src/test/run-pass/cci_no_inline_exe.rs
@@ -1,3 +1,4 @@
+// xfail-fast - check-fast doesn't understand aux-build
 // aux-build:cci_no_inline_lib.rs
 
 use std;