diff --git a/repos/libports/src/lib/libc/dummies.cc b/repos/libports/src/lib/libc/dummies.cc
index 37c2c83f8..150640ddf 100644
--- a/repos/libports/src/lib/libc/dummies.cc
+++ b/repos/libports/src/lib/libc/dummies.cc
@@ -221,5 +221,11 @@ int __attribute__((weak)) madvise(void *addr, size_t length, int advice)
 
 const struct res_sym __p_type_syms[] = { };
 
+#define DUMMY_EPERM(ret_type, ret_val, name, args) __attribute__((weak)) \
+ret_type name args { errno = EPERM; return ret_val; }
+
+DUMMY_EPERM(int, -1,   mlock, (const void *, size_t));
+DUMMY_EPERM(int, -1, munlock, (const void *, size_t));
+
 } /* extern "C" */