diff --git a/userspace/libraries/LibC/stdio.cpp b/userspace/libraries/LibC/stdio.cpp
index 6a68f1136b..452c93a2bb 100644
--- a/userspace/libraries/LibC/stdio.cpp
+++ b/userspace/libraries/LibC/stdio.cpp
@@ -705,8 +705,11 @@ char* tmpnam(char* storage)
 	return storage;
 }
 
-// TODO
-int ungetc(int, FILE*);
+int ungetc(int c, FILE* stream)
+{
+	dwarnln("FIXME: ungetc({}, {})", c, stream);
+	ASSERT_NOT_REACHED();
+}
 
 int vfprintf(FILE* file, const char* format, va_list arguments)
 {
diff --git a/userspace/libraries/LibC/termios.cpp b/userspace/libraries/LibC/termios.cpp
index e2b749ddec..b81c9ecb1b 100644
--- a/userspace/libraries/LibC/termios.cpp
+++ b/userspace/libraries/LibC/termios.cpp
@@ -1,3 +1,6 @@
+#include <BAN/Assert.h>
+#include <BAN/Debug.h>
+
 #include <errno.h>
 #include <sys/syscall.h>
 #include <termios.h>
@@ -65,7 +68,11 @@ int tcdrain(int);
 
 int tcflow(int, int);
 
-int tcflush(int, int);
+int tcflush(int fd, int queue_selector)
+{
+	dwarnln("FIXME: tcflush({}, {})", fd, queue_selector);
+	ASSERT_NOT_REACHED();
+}
 
 int tcgetattr(int fildes, struct termios* termios)
 {
diff --git a/userspace/libraries/LibC/unistd.cpp b/userspace/libraries/LibC/unistd.cpp
index d3afcfbf60..3ae50e085b 100644
--- a/userspace/libraries/LibC/unistd.cpp
+++ b/userspace/libraries/LibC/unistd.cpp
@@ -1,5 +1,7 @@
 #include <BAN/Assert.h>
+#include <BAN/Debug.h>
 #include <kernel/Syscall.h>
+
 #include <errno.h>
 #include <pwd.h>
 #include <stdarg.h>
@@ -534,3 +536,9 @@ unsigned alarm(unsigned seconds)
 	setitimer(ITIMER_REAL, &value, &ovalue);
 	return ovalue.it_value.tv_sec;
 }
+
+int symlink(const char* path1, const char* path2)
+{
+	dwarnln("FIXME: symlink({}, {})", path1, path2);
+	ASSERT_NOT_REACHED();
+}