diff --git a/04/main.go b/04/main.go
index 8eb6c0f..cf0fddf 100644
--- a/04/main.go
+++ b/04/main.go
@@ -54,6 +54,19 @@ func contains(i int, a []int) bool {
 	return false
 }
 
+func bingo(set map[int]struct{}, drawnNumbers []int) bool {
+	hits := 0
+	for _, i := range drawnNumbers {
+		if _, ok := set[i]; ok {
+			hits++
+		}
+	}
+	if hits == 5 {
+		return true
+	}
+	return false
+}
+
 // a bingo card like this:
 // 60 79 46  9 58
 // 97 81  6 94 84
@@ -75,21 +88,10 @@ type bingoCard struct {
 
 func readBingoCard(scanner *bufio.Scanner) bingoCard {
 	card := bingoCard{
-		allNumbers: make([]int, 0),
-		rows:       make([]map[int]struct{}, 5),
-		columns:    make([]map[int]struct{}, 5),
+		allNumbers: []int{},
+		rows:       []map[int]struct{}{0: {}, 1: {}, 2: {}, 3: {}, 4: {}},
+		columns:    []map[int]struct{}{0: {}, 1: {}, 2: {}, 3: {}, 4: {}},
 	}
-	// what a pain
-	card.rows[0] = make(map[int]struct{})
-	card.rows[1] = make(map[int]struct{})
-	card.rows[2] = make(map[int]struct{})
-	card.rows[3] = make(map[int]struct{})
-	card.rows[4] = make(map[int]struct{})
-	card.columns[0] = make(map[int]struct{})
-	card.columns[1] = make(map[int]struct{})
-	card.columns[2] = make(map[int]struct{})
-	card.columns[3] = make(map[int]struct{})
-	card.columns[4] = make(map[int]struct{})
 
 	for i := 0; i < 5; i++ {
 		scanner.Scan()
@@ -110,24 +112,12 @@ func readBingoCard(scanner *bufio.Scanner) bingoCard {
 
 func checkBoard(currentNumbers []int, card bingoCard) bool {
 	for _, row := range card.rows {
-		hits := 0
-		for _, i := range currentNumbers {
-			if _, ok := row[i]; ok {
-				hits++
-			}
-		}
-		if hits == 5 {
+		if bingo(row, currentNumbers) {
 			return true
 		}
 	}
 	for _, col := range card.columns {
-		hits := 0
-		for _, i := range currentNumbers {
-			if _, ok := col[i]; ok {
-				hits++
-			}
-		}
-		if hits == 5 {
+		if bingo(col, currentNumbers) {
 			return true
 		}
 	}