diff --git a/options/internal/include/mlibc/sysdeps.hpp b/options/internal/include/mlibc/sysdeps.hpp
index 1850f1d5..c3c7cd02 100644
--- a/options/internal/include/mlibc/sysdeps.hpp
+++ b/options/internal/include/mlibc/sysdeps.hpp
@@ -28,6 +28,7 @@ int sys_isatty(int fd, int *ptr);
 int sys_stat(const char *pathname, struct stat *statbuf);
 int sys_fstat(int fd, struct stat *statbuf);
 int sys_readlink(const char *path, void *buffer, size_t max_size, ssize_t *length);
+int sys_ftruncate(int fd, size_t size);
 int sys_fallocate(int fd, off_t offset, size_t size);
 int sys_unlink(const char *path);
 int sys_socket(int family, int type, int protocol, int *fd);
diff --git a/options/posix/generic/unistd-stubs.cpp b/options/posix/generic/unistd-stubs.cpp
index bebc708d..c75a23c5 100644
--- a/options/posix/generic/unistd-stubs.cpp
+++ b/options/posix/generic/unistd-stubs.cpp
@@ -98,9 +98,10 @@ int fsync(int) {
 	__ensure(!"Not implemented");
 	__builtin_unreachable();
 }
-int ftruncate(int, off_t) {
-	__ensure(!"Not implemented");
-	__builtin_unreachable();
+int ftruncate(int fd, off_t size) {
+	if(mlibc::sys_ftruncate(fd, size))
+		return -1;
+	return 0;
 }
 char *getcwd(char *, size_t) {
 	__ensure(!"Not implemented");
diff --git a/sysdeps/managarm/generic/file.cpp b/sysdeps/managarm/generic/file.cpp
index eed28aac..d7bab2d2 100644
--- a/sysdeps/managarm/generic/file.cpp
+++ b/sysdeps/managarm/generic/file.cpp
@@ -298,7 +298,7 @@ int sys_vm_map(void *hint, size_t size, int prot, int flags, int fd, off_t offse
 }
 
 int sys_vm_unmap(void *pointer, size_t size) {
-	HEL_CHECK(helUnmapMemory(kHelNullHandle, pointer, size));
+	HEL_CHECK(helUnmapMemory(kHelNullHandle, pointer, (size + 0xFFF) & ~size_t(0xFFF)));
 	return 0;
 }
 
@@ -1938,6 +1938,45 @@ int sys_readlink(const char *path, void *data, size_t max_size, ssize_t *length)
 	}
 }
 
+int sys_ftruncate(int fd, size_t size) {
+	HelAction actions[3];
+	globalQueue.trim();
+
+	auto handle = cacheFileTable()[fd];
+	__ensure(handle);
+	
+	managarm::fs::CntRequest<MemoryAllocator> req(getAllocator());
+	req.set_req_type(managarm::fs::CntReqType::PT_TRUNCATE);
+	req.set_size(size);
+
+	frigg::String<MemoryAllocator> ser(getAllocator());
+	req.SerializeToString(&ser);
+	actions[0].type = kHelActionOffer;
+	actions[0].flags = kHelItemAncillary;
+	actions[1].type = kHelActionSendFromBuffer;
+	actions[1].flags = kHelItemChain;
+	actions[1].buffer = ser.data();
+	actions[1].length = ser.size();
+	actions[2].type = kHelActionRecvInline;
+	actions[2].flags = 0;
+	HEL_CHECK(helSubmitAsync(handle, actions, 3,
+			globalQueue.getQueue(), 0, 0));
+
+	auto element = globalQueue.dequeueSingle();
+	auto offer = parseSimple(element);
+	auto send_req = parseSimple(element);
+	auto recv_resp = parseInline(element);
+
+	HEL_CHECK(offer->error);
+	HEL_CHECK(send_req->error);
+	HEL_CHECK(recv_resp->error);
+
+	managarm::fs::SvrResponse<MemoryAllocator> resp(getAllocator());
+	resp.ParseFromArray(recv_resp->data, recv_resp->length);
+	__ensure(resp.error() == managarm::fs::Errors::SUCCESS);
+	return 0;
+}
+
 int sys_fallocate(int fd, off_t offset, size_t size) {
 	HelAction actions[3];
 	globalQueue.trim();