diff --git a/backend/internal/handlers/global_state.go b/backend/internal/handlers/global_state.go
index 415b215..2378f7b 100644
--- a/backend/internal/handlers/global_state.go
+++ b/backend/internal/handlers/global_state.go
@@ -267,6 +267,14 @@ func (gs *GState) SubmitWeeklyReport(c *fiber.Ctx) error {
 		return c.Status(400).SendString(err.Error())
 	}
 
+	// Make sure all the fields of the report are valid
+	if report.Week < 1 || report.Week > 52 {
+		return c.Status(400).SendString("Invalid week number")
+	}
+	if report.DevelopmentTime < 0 || report.MeetingTime < 0 || report.AdminTime < 0 || report.OwnWorkTime < 0 || report.StudyTime < 0 || report.TestingTime < 0 {
+		return c.Status(400).SendString("Invalid time report")
+	}
+
 	if err := gs.Db.AddWeeklyReport(report.ProjectName, username, report.Week, report.DevelopmentTime, report.MeetingTime, report.AdminTime, report.OwnWorkTime, report.StudyTime, report.TestingTime); err != nil {
 		return c.Status(500).SendString(err.Error())
 	}