diff --git a/cpython/pyconfig.undefs.h b/cpython/pyconfig.undefs.h
index 68a4d0c57..27f7981bb 100644
--- a/cpython/pyconfig.undefs.h
+++ b/cpython/pyconfig.undefs.h
@@ -4,3 +4,28 @@
 #undef HAVE_SOCKETPAIR
 #undef HAVE_UTIMENSAT
 #undef HAVE_SIGACTION
+
+/* Untested syscalls in emscripten */
+#undef HAVE_OPENAT
+#undef HAVE_MKDIRAT
+#undef HAVE_FCHOWNAT
+#undef HAVE_RENAMEAT
+#undef HAVE_LINKAT
+#undef HAVE_SYMLINKAT
+#undef HAVE_READLINKAT
+#undef HAVE_FCHMODAT
+#undef HAVE_DUP3
+
+/* Syscalls not implemented in emscripten */
+#undef HAVE_PREADV
+#undef HAVE_PWRITEV
+#undef HAVE_PIPE2
+#undef HAVE_NICE
+
+/* Syscalls that resulted in a segfault */
+#undef HAVE_UTIMENSAT
+#undef HAVE_SYS_IOCTL_H
+#undef HAVE_SYS_SOCKET_H
+
+/* Unsupported functionality */
+#undef HAVE_PTHREAD_H