diff --git a/kernel/syscall.c b/kernel/syscall.c
index 305e404b..5edd4501 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -143,8 +143,9 @@ int syscall_handler(uint32_t sys_nr, ...)
 			int fd = va_arg(vl, int);
 			const char* buf = va_arg(vl, const char*);
 			size_t len = va_arg(vl, size_t);
-			ret = write_fs(&(per_core(current_task)->fildes_table[fd]),
-				(uint8_t*)buf, len);
+			if (fd >= 0)
+				ret = write_fs(&(per_core(current_task)->fildes_table[fd]),
+					(uint8_t*)buf, len);
 			break;
 		}
 	case __NR_open: {
@@ -156,22 +157,25 @@ int syscall_handler(uint32_t sys_nr, ...)
 		}
 	case __NR_close: {
 			int fd = va_arg(vl, int);
-			ret = sys_close(fd);
+			if (fd >= 0)
+				ret = sys_close(fd);
  			break;
  		}
 	case __NR_read: {
 			int fd = va_arg(vl, int);
 			const char* buf = va_arg(vl, const char*);
  			size_t len = va_arg(vl, size_t);
-			ret = read_fs(&(per_core(current_task)->fildes_table[fd]), 
-				(uint8_t*)buf, len);
+			if (fd >= 0)
+				ret = read_fs(&(per_core(current_task)->fildes_table[fd]), 
+					(uint8_t*)buf, len);
 			break;
 		}
 	case __NR_lseek: {
 			int fd = va_arg(vl, int);
 			off_t pos = va_arg(vl, off_t);
  			int origin = va_arg(vl, int);
-			ret = sys_lseek(fd, pos, origin);
+			if (fd >= 0)
+				ret = sys_lseek(fd, pos, origin);
 			break;
 		}
 	case __NR_sbrk: {
diff --git a/newlib/examples/hello.c b/newlib/examples/hello.c
index 7edfe01d..b6bf5ef6 100644
--- a/newlib/examples/hello.c
+++ b/newlib/examples/hello.c
@@ -47,6 +47,7 @@ int main(int argc, char** argv)
 	write(testfile, "test", 4);
 	lseek(testfile, 0, SEEK_SET);
 	read(testfile, teststr, 100);
+	close(testfile);
 	printf("Gelesen aus neuer Datei: %s", teststr);
 
 	return errno;