diff --git a/godeltaprof/block.go b/godeltaprof/block.go
index 10c9d00..9a7000c 100644
--- a/godeltaprof/block.go
+++ b/godeltaprof/block.go
@@ -50,7 +50,6 @@ func NewMutexProfiler() *BlockProfiler {
 	}
 }
 
-// todo document
 func NewMutexProfilerWithOptions(options ProfileOptions) *BlockProfiler {
 	return &BlockProfiler{
 		runtimeProfile: runtime.MutexProfile,
@@ -83,7 +82,6 @@ func NewBlockProfiler() *BlockProfiler {
 	}
 }
 
-// todo document
 func NewBlockProfilerWithOptions(options ProfileOptions) *BlockProfiler {
 	return &BlockProfiler{
 		runtimeProfile: runtime.BlockProfile,
diff --git a/godeltaprof/compat/stub_go20_test.go b/godeltaprof/compat/stub_go20_test.go
index ba0d649..69facb8 100644
--- a/godeltaprof/compat/stub_go20_test.go
+++ b/godeltaprof/compat/stub_go20_test.go
@@ -1,24 +1,16 @@
-//go:build go1.20
+//go:build go1.16 && !go1.21
 
 package compat
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestRuntimeFrameSymbolName(t *testing.T) {
-	checkSignature(t, "runtime/pprof",
-		"runtime_FrameSymbolName",
-		"func runtime/pprof.runtime_FrameSymbolName(f *runtime.Frame) string")
 	checkSignature(t, "github.com/grafana/pyroscope-go/godeltaprof/internal/pprof",
 		"runtime_FrameSymbolName",
 		"func github.com/grafana/pyroscope-go/godeltaprof/internal/pprof.runtime_FrameSymbolName(f *runtime.Frame) string")
 }
 
 func TestRuntimeFrameStartLine(t *testing.T) {
-	checkSignature(t, "runtime/pprof",
-		"runtime_FrameStartLine",
-		"func runtime/pprof.runtime_FrameStartLine(f *runtime.Frame) int")
 	checkSignature(t, "github.com/grafana/pyroscope-go/godeltaprof/internal/pprof",
 		"runtime_FrameStartLine",
 		"func github.com/grafana/pyroscope-go/godeltaprof/internal/pprof.runtime_FrameStartLine(f *runtime.Frame) int")
diff --git a/godeltaprof/compat/stub_go19_test.go b/godeltaprof/compat/stub_go21_test.go
similarity index 64%
rename from godeltaprof/compat/stub_go19_test.go
rename to godeltaprof/compat/stub_go21_test.go
index 1d4f5f4..eda7f6b 100644
--- a/godeltaprof/compat/stub_go19_test.go
+++ b/godeltaprof/compat/stub_go21_test.go
@@ -1,16 +1,24 @@
-//go:build go1.16 && !go1.20
+//go:build go1.21
 
 package compat
 
-import "testing"
+import (
+	"testing"
+)
 
 func TestRuntimeFrameSymbolName(t *testing.T) {
+	checkSignature(t, "runtime/pprof",
+		"runtime_FrameSymbolName",
+		"func runtime/pprof.runtime_FrameSymbolName(f *runtime.Frame) string")
 	checkSignature(t, "github.com/grafana/pyroscope-go/godeltaprof/internal/pprof",
 		"runtime_FrameSymbolName",
 		"func github.com/grafana/pyroscope-go/godeltaprof/internal/pprof.runtime_FrameSymbolName(f *runtime.Frame) string")
 }
 
 func TestRuntimeFrameStartLine(t *testing.T) {
+	checkSignature(t, "runtime/pprof",
+		"runtime_FrameStartLine",
+		"func runtime/pprof.runtime_FrameStartLine(f *runtime.Frame) int")
 	checkSignature(t, "github.com/grafana/pyroscope-go/godeltaprof/internal/pprof",
 		"runtime_FrameStartLine",
 		"func github.com/grafana/pyroscope-go/godeltaprof/internal/pprof.runtime_FrameStartLine(f *runtime.Frame) int")
diff --git a/godeltaprof/heap.go b/godeltaprof/heap.go
index 024c7ad..f619307 100644
--- a/godeltaprof/heap.go
+++ b/godeltaprof/heap.go
@@ -41,7 +41,6 @@ func NewHeapProfiler() *HeapProfiler {
 		}}
 }
 
-// todo document
 func NewHeapProfilerWithOptions(options ProfileOptions) *HeapProfiler {
 	return &HeapProfiler{
 		impl: pprof.DeltaHeapProfiler{