diff --git a/pkg/takuzu/core.go b/pkg/takuzu/core.go
index b2177a0..49a3af7 100644
--- a/pkg/takuzu/core.go
+++ b/pkg/takuzu/core.go
@@ -5,7 +5,7 @@ import "errors"
 // Create a new instance of Takuzu Core with given size
 func NewCore(size int) (*Core, error) {
 
-	if size < 4 || size > 12 {
+	if size < 4 || size > 12 || size%2 != 0 {
 		return &Core{}, errors.New(incorrectSize)
 	}