diff --git a/hermit/include/hermit/syscall.h b/hermit/include/hermit/syscall.h
index 541e226a4..f56b03b76 100644
--- a/hermit/include/hermit/syscall.h
+++ b/hermit/include/hermit/syscall.h
@@ -71,7 +71,7 @@ int sys_setprio(tid_t* id, int prio);
 void NORETURN sys_exit(int arg);
 ssize_t sys_read(int fd, char* buf, size_t len);
 ssize_t sys_write(int fd, const char* buf, size_t len);
-ssize_t sys_sbrk(int incr);
+ssize_t sys_sbrk(ssize_t incr);
 int sys_open(const char* name, int flags, int mode);
 int sys_close(int fd);
 void sys_msleep(unsigned int ms);
diff --git a/hermit/kernel/syscall.c b/hermit/kernel/syscall.c
index 599c415b1..13a0fd7cd 100644
--- a/hermit/kernel/syscall.c
+++ b/hermit/kernel/syscall.c
@@ -218,7 +218,7 @@ ssize_t writev(int fildes, const struct iovec *iov, int iovcnt)
 	return -ENOSYS;
 }
 
-ssize_t sys_sbrk(int incr)
+ssize_t sys_sbrk(ssize_t incr)
 {
 	task_t* task = per_core(current_task);
 	vma_t* heap = task->heap;
diff --git a/hermit/usr/newlib b/hermit/usr/newlib
index 168997d74..3aee92a10 160000
--- a/hermit/usr/newlib
+++ b/hermit/usr/newlib
@@ -1 +1 @@
-Subproject commit 168997d7430a644282c31912ac8c3cdce668c248
+Subproject commit 3aee92a10b8e7bcbf7158287cb4561da5f86fdc9