diff --git a/Userland/Libraries/LibCore/DateTime.h b/Userland/Libraries/LibCore/DateTime.h
index 46b6014ade..1e24751038 100644
--- a/Userland/Libraries/LibCore/DateTime.h
+++ b/Userland/Libraries/LibCore/DateTime.h
@@ -29,10 +29,10 @@ public:
     unsigned day_of_year() const;
     bool is_leap_year() const;
 
-    void set_time(int year, int month = 1, int day = 0, int hour = 0, int minute = 0, int second = 0);
+    void set_time(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
     String to_string(const String& format = "%Y-%m-%d %H:%M:%S") const;
 
-    static DateTime create(int year, int month = 1, int day = 0, int hour = 0, int minute = 0, int second = 0);
+    static DateTime create(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
     static DateTime now();
     static DateTime from_timestamp(time_t);
     static Optional<DateTime> parse(const String& format, const String& string);