diff --git a/userspace/libraries/LibC/stdio.cpp b/userspace/libraries/LibC/stdio.cpp
index 164f82fd..acd56e1a 100644
--- a/userspace/libraries/LibC/stdio.cpp
+++ b/userspace/libraries/LibC/stdio.cpp
@@ -169,7 +169,7 @@ static mode_t parse_mode_string(const char* mode_str)
 		return 0;
 	if (len == 3 && mode_str[1] == mode_str[2])
 		return 0;
-	if (strspn(mode_str + 1, "b+") != len - 1)
+	if (strspn(mode_str + 1, "tb+") != len - 1)
 		return 0;
 	bool plus = (mode_str[1] == '+' || mode_str[2] == '+');
 	switch (mode_str[0])