diff --git mlibc-clean/options/ansi/generic/wchar.cpp mlibc-workdir/options/ansi/generic/wchar.cpp
index b44ebc2..9339316 100644
--- mlibc-clean/options/ansi/generic/wchar.cpp
+++ mlibc-workdir/options/ansi/generic/wchar.cpp
@@ -54,8 +54,13 @@ size_t mbrlen(const char *__restrict mbs, size_t mb_limit, mbstate_t *__restrict
 
 	mlibc::code_seq<const char> nseq{mbs, mbs + mb_limit};
 	mlibc::code_seq<wchar_t> wseq{&wc, &wc + 1};
-	if(auto e = cc->decode_wtranscode(nseq, wseq, *stp); e != mlibc::charcode_error::null)
-		__ensure(!"decode_wtranscode() errors are not handled");
+	if(auto e = cc->decode_wtranscode(nseq, wseq, *stp); e != mlibc::charcode_error::null) {
+		if(e == mlibc::charcode_error::input_underflow)
+			return static_cast<size_t>(-1);
+		__ensure(e == mlibc::charcode_error::illegal_input);
+		errno = EILSEQ;
+		return static_cast<size_t>(-1);
+	}
 	return nseq.it - mbs;
 }
 
diff --git mlibc-clean/options/glibc/generic/execinfo.cpp mlibc-workdir/options/glibc/generic/execinfo.cpp
index 1ed110d..ded9114 100644
--- mlibc-clean/options/glibc/generic/execinfo.cpp
+++ mlibc-workdir/options/glibc/generic/execinfo.cpp
@@ -4,6 +4,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <unwind.h>
+#include <errno.h>
 
 #include <bits/ensure.h>
 #include <mlibc/debug.hpp>
@@ -52,29 +53,7 @@ _Unwind_Reason_Code trace(_Unwind_Context *context, void *arg) {
 } // namespace
 
 int backtrace(void **buffer, int size) {
-	if (size <= 0)
-		return 0;
-
-	if (!libgccHandle) {
-		libgccHandle = dlopen("libgcc_s.so.1", RTLD_LAZY | RTLD_LOCAL);
-		if (!libgccHandle || libgccHandle.value() == nullptr) {
-			auto error = dlerror();
-			mlibc::infoLogger() << "Failed to load libgcc_s.so.1: " << (error ? error : "") << frg::endlog;
-			return 0;
-		}
-
-		unwindBacktrace = reinterpret_cast<UnwindBacktrace>(dlsym(libgccHandle.value(), "_Unwind_Backtrace"));
-		unwindGetIP = reinterpret_cast<UnwindGetIP>(dlsym(libgccHandle.value(), "_Unwind_GetIP"));
-
-		if (!unwindBacktrace || !unwindGetIP) {
-			mlibc::infoLogger() << "Failed to find unwind functions in libgcc_s.so.1: " << dlerror() << frg::endlog;
-			return 0;
-		}
-	}
-
-	UnwindState state{buffer, size};
-	unwindBacktrace(trace, &state);
-	return state.current_frame;
+	return ENOSYS;
 }
 
 char **backtrace_symbols(void *const *, int) {
@@ -82,25 +61,5 @@ char **backtrace_symbols(void *const *, int) {
 	__builtin_unreachable();
 }
 
-void backtrace_symbols_fd(void *const *buffer, int size, int fd) {
-	if (size <= 0 || fd < 0)
-		return;
-
-	for (int frame_num = 0; frame_num < size; frame_num++) {
-		Dl_info info;
-		if (dladdr(buffer[frame_num], &info) != 0) {
-			if (info.dli_fname != nullptr)
-				write(fd, info.dli_fname, strlen(info.dli_fname));
-
-			if (info.dli_sname != nullptr)
-				dprintf(fd, "(%s+0x%" PRIxPTR ") ", info.dli_sname,
-					reinterpret_cast<uintptr_t>(buffer[frame_num]) - reinterpret_cast<uintptr_t>(info.dli_saddr));
-			else if(info.dli_saddr)
-				dprintf(fd, "(+%p) ", info.dli_saddr);
-			else
-				dprintf(fd, "() ");
-		}
-
-		dprintf(fd, "[%p]\n", buffer[frame_num]);
-	}
+void backtrace_symbols_fd(void *const *, int, int) {
 }
diff --git mlibc-clean/sysdeps/astral/generic/generic.cpp mlibc-workdir/sysdeps/astral/generic/generic.cpp
index 939925e..5ee7fad 100644
--- mlibc-clean/sysdeps/astral/generic/generic.cpp
+++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
@@ -47,6 +47,12 @@ namespace mlibc {
 		return 0;
 	}
 
+	int sys_unlockpt(int fd) {
+		int r;
+		// unlockpt is a no-op kernel side, so use this to check for an invalid pty
+		return sys_ioctl(fd, 0x13376167, NULL, &r);
+	}
+
 	int sys_readv(int fd, const struct iovec *iovs, int iovc, ssize_t *bytes_read) {
 		long r;
 		int error = syscall(SYSCALL_READV, &r, fd, (uint64_t)iovs, iovc);
diff --git mlibc-clean/sysdeps/astral/include/astral/archctl.h mlibc-workdir/sysdeps/astral/include/astral/archctl.h
index 7e4f2a1..a5f382d 100644
--- mlibc-clean/sysdeps/astral/include/astral/archctl.h
+++ mlibc-workdir/sysdeps/astral/include/astral/archctl.h
@@ -5,6 +5,11 @@
 #define ARCH_CTL_SET_FSBASE 1
 #define ARCH_CTL_GET_GSBASE 2
 #define ARCH_CTL_GET_FSBASE 3
+#define ARCH_CTL_SET_SYSTRACE 4
+
+#define ARCH_CTL_SYSTRACE_OFF 0
+#define ARCH_CTL_SYSTRACE_SELF 1
+#define ARCH_CTL_SYSTRACE_ALL 2
 
 #ifdef __cplusplus
 extern "C" {