diff --git a/internal/log/logger.go b/internal/log/logger.go
index 99aaf4cc68..07aac3fe9a 100644
--- a/internal/log/logger.go
+++ b/internal/log/logger.go
@@ -8,6 +8,7 @@ import (
 	"runtime"
 	"time"
 
+	"github.com/benbjohnson/clock"
 	"golang.org/x/exp/maps"
 )
 
@@ -29,6 +30,7 @@ type Logger struct {
 	level      Level
 	attributes map[string]string
 	sink       Sink
+	clock      clock.Clock
 }
 
 // New returns a new logger.
@@ -37,6 +39,7 @@ func New(level Level, sink Sink) *Logger {
 		level:      level,
 		attributes: map[string]string{},
 		sink:       sink,
+		clock:      clock.New(),
 	}
 }
 
@@ -72,11 +75,11 @@ func (l *Logger) Log(entry Entry) {
 		return
 	}
 	if entry.Time.IsZero() {
-		entry.Time = time.Now()
+		// Use UTC now
+		entry.Time = l.clock.Now().UTC()
 	}
 
-	// merge logger and entry attributes
-	mergedAttributes := make(map[string]string)
+	mergedAttributes := make(map[string]string, len(l.attributes)+len(entry.Attributes))
 	maps.Copy(mergedAttributes, l.attributes)
 	maps.Copy(mergedAttributes, entry.Attributes)
 	entry.Attributes = mergedAttributes
diff --git a/internal/log/logger_test.go b/internal/log/logger_test.go
new file mode 100644
index 0000000000..7af86da748
--- /dev/null
+++ b/internal/log/logger_test.go
@@ -0,0 +1,33 @@
+package log
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/alecthomas/assert/v2"
+	"github.com/benbjohnson/clock"
+)
+
+func TestLogger(t *testing.T) {
+	w := &strings.Builder{}
+	log := New(Trace, newJSONSink(w))
+	log.clock = clock.NewMock()
+	log.Tracef("trace: %s", "trace")
+	log.Debugf("debug: %s", "debug")
+	log.Infof("info: %s", "info")
+	log.Warnf("warn: %s", "warn")
+	log.Errorf(errors.New("error"), "error: %s", "error")
+	log = log.Scope("scoped").Attrs(map[string]string{"key": "value"})
+	log.Tracef("trace: %s", "trace")
+	log.Log(Entry{Level: Trace, Message: "trace: trace"})
+	assert.Equal(t, strings.TrimSpace(`
+{"level":"trace","message":"trace: trace","time":"1970-01-01T00:00:00Z"}
+{"level":"debug","message":"debug: debug","time":"1970-01-01T00:00:00Z"}
+{"level":"info","message":"info: info","time":"1970-01-01T00:00:00Z"}
+{"level":"warn","message":"warn: warn","time":"1970-01-01T00:00:00Z"}
+{"level":"error","message":"error: error: error","time":"1970-01-01T00:00:00Z","error":"error"}
+{"level":"trace","attributes":{"key":"value","scope":"scoped"},"message":"trace: trace","time":"1970-01-01T00:00:00Z"}
+{"level":"trace","attributes":{"key":"value","scope":"scoped"},"message":"trace: trace","time":"1970-01-01T00:00:00Z"}
+`)+"\n", w.String())
+}