diff --git a/LibC/crt0.cpp b/LibC/crt0.cpp
index c7bf35b2be..ee307daa81 100644
--- a/LibC/crt0.cpp
+++ b/LibC/crt0.cpp
@@ -38,9 +38,6 @@ int _start(int argc, char** argv, char** env)
 
     int status = main(argc, argv);
 
-    fflush(stdout);
-    fflush(stderr);
-
     exit(status);
 
     return 20150614;
diff --git a/LibC/fcntl.h b/LibC/fcntl.h
index ab0f2167e7..5f67104bf3 100644
--- a/LibC/fcntl.h
+++ b/LibC/fcntl.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <sys/cdefs.h>
+#include <sys/types.h>
 
 __BEGIN_DECLS
 
@@ -54,4 +55,17 @@ __BEGIN_DECLS
 
 int fcntl(int fd, int cmd, ...);
 
+#define F_WRLCK 1
+#define F_UNLCK 2
+
+#define F_SETLKW 7
+
+struct flock {
+    short l_type;
+    short l_whence;
+    off_t l_start;
+    off_t l_len;
+    pid_t l_pid;
+};
+
 __END_DECLS
diff --git a/LibC/stdio.cpp b/LibC/stdio.cpp
index 88ca23d82c..e94ac7322a 100644
--- a/LibC/stdio.cpp
+++ b/LibC/stdio.cpp
@@ -440,7 +440,8 @@ int fclose(FILE* stream)
 {
     fflush(stream);
     int rc = close(stream->fd);
-    free(stream);
+    if (stream != &__default_streams[0] && stream != &__default_streams[1] && stream != &__default_streams[2] && stream != &__default_streams[3])
+        free(stream);
     return rc;
 }
 
@@ -510,6 +511,11 @@ int vfscanf(FILE* stream, const char* fmt, va_list ap)
     return vsscanf(buffer, fmt, ap);
 }
 
+FILE* tmpfile()
+{
+    dbgprintf("FIXME: Implement tmpfile()\n");
+    ASSERT_NOT_REACHED();
+}
 
 }
 
diff --git a/LibC/stdlib.cpp b/LibC/stdlib.cpp
index d83a25a4a9..e9b70dbf0f 100644
--- a/LibC/stdlib.cpp
+++ b/LibC/stdlib.cpp
@@ -26,6 +26,8 @@ void exit(int status)
         __atexit_handlers[i]();
     extern void _fini();
     _fini();
+    fflush(stdout);
+    fflush(stderr);
     _exit(status);
     ASSERT_NOT_REACHED();
 }
@@ -41,7 +43,7 @@ int atexit(void (*handler)())
 void abort()
 {
     // FIXME: Implement proper abort().
-    exit(253);
+    CRASH();
 }
 
 char* getenv(const char* name)