diff --git a/year25/day1.go b/year25/day1.go
index c800362..f824901 100644
--- a/year25/day1.go
+++ b/year25/day1.go
@@ -5,11 +5,10 @@ import (
 	"fmt"
 	"io"
 	"iter"
-	"log"
 	"strconv"
 )
 
-func Day1Part1(r io.Reader, l *log.Logger) (any, error) {
+func Day1Part1(r io.Reader, l Logger) (any, error) {
 	dial := 50
 	solution := 0
 	for pair := range day1GetPairs(r) {
@@ -27,7 +26,7 @@ func Day1Part1(r io.Reader, l *log.Logger) (any, error) {
 	return solution, nil
 }
 
-func Day1Part2Slow(r io.Reader, l *log.Logger) (any, error) {
+func Day1Part2Slow(r io.Reader, l Logger) (any, error) {
 	dial := 50
 	solution := 0
 	for pair := range day1GetPairs(r) {
@@ -45,7 +44,7 @@ func Day1Part2Slow(r io.Reader, l *log.Logger) (any, error) {
 	return solution, nil
 }
 
-func Day1Part2Fast(r io.Reader, l *log.Logger) (any, error) {
+func Day1Part2Fast(r io.Reader, l Logger) (any, error) {
 	dial := 50
 	solution := 0
 	for pair := range day1GetPairs(r) {
diff --git a/year25/day2.go b/year25/day2.go
index e226e4b..ce3d4dc 100644
--- a/year25/day2.go
+++ b/year25/day2.go
@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"log"
 	"strconv"
 	"strings"
 
@@ -51,7 +50,7 @@ func (s *day2Scanner) Bounds() (int, int) {
 	return s.a, s.b
 }
 
-func Day2Part1Simple(r io.Reader, l *log.Logger) (any, error) {
+func Day2Part1Simple(r io.Reader, l Logger) (any, error) {
 	input, err := aocutils.ReadString(r)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read input: %s", err)
@@ -95,7 +94,7 @@ func Day2Part1Simple(r io.Reader, l *log.Logger) (any, error) {
 	return sum, nil
 }
 
-func Day2Part2Simple(r io.Reader, l *log.Logger) (any, error) {
+func Day2Part2Simple(r io.Reader, l Logger) (any, error) {
 	input, err := aocutils.ReadString(r)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read input: %s", err)
@@ -155,7 +154,7 @@ func Day2Part2Simple(r io.Reader, l *log.Logger) (any, error) {
 	return sum, nil
 }
 
-func Day2Part1(r io.Reader, logger *log.Logger) (any, error) {
+func Day2Part1(r io.Reader, logger Logger) (any, error) {
 	inputScanner := bufio.NewScanner(r)
 	inputScanner.Split(aocutils.SplitComma)
 	scanner := &day2Scanner{scanner: inputScanner, sep: '-'}
@@ -182,7 +181,7 @@ func Day2Part1(r io.Reader, logger *log.Logger) (any, error) {
 	return sum, scanner.Err()
 }
 
-func Day2Part2(r io.Reader, logger *log.Logger) (any, error) {
+func Day2Part2(r io.Reader, logger Logger) (any, error) {
 	inputScanner := bufio.NewScanner(r)
 	inputScanner.Split(aocutils.SplitComma)
 
diff --git a/year25/day3.go b/year25/day3.go
index 07d8519..8462e6e 100644
--- a/year25/day3.go
+++ b/year25/day3.go
@@ -4,17 +4,16 @@ import (
 	"bufio"
 	"fmt"
 	"io"
-	"log"
 	"strings"
 )
 
-func Day3Part1(r io.Reader, l *log.Logger) (any, error) {
+func Day3Part1(r io.Reader, l Logger) (any, error) {
 	return Day3(r, l, 2)
 }
-func Day3Part2(r io.Reader, l *log.Logger) (any, error) {
+func Day3Part2(r io.Reader, l Logger) (any, error) {
 	return Day3(r, l, 12)
 }
-func Day3(r io.Reader, logger *log.Logger, size int) (int64, error) {
+func Day3(r io.Reader, logger Logger, size int) (int64, error) {
 	scanner := bufio.NewScanner(r)
 	scanner.Split(bufio.ScanLines)
 	var sum int64
diff --git a/year25/utils.go b/year25/utils.go
new file mode 100644
index 0000000..a4ad4ec
--- /dev/null
+++ b/year25/utils.go
@@ -0,0 +1,6 @@
+package year25
+
+type Logger interface {
+	Printf(string, ...interface{})
+	Println(...interface{})
+}