diff --git a/tests/filter_libc b/tests/filter_libc
index 5d8e0ac..9a508b0 100755
--- a/tests/filter_libc
+++ b/tests/filter_libc
@@ -36,6 +36,9 @@ while (<>)
     s/(at.*)__builtin_vec_delete/$1...operator delete[].../;
     s/(at.*)operator delete\[\]\(void\*\)/$1...operator delete[].../;
 
+    # Some glibc versions complain about unexpected futex syscall errors.
+    s/The futex facility returned an unexpected error code.//;
+
     print;
 }