diff --git a/builder/config.go b/builder/config.go
index f9fe715b76..66eea404e0 100644
--- a/builder/config.go
+++ b/builder/config.go
@@ -33,7 +33,7 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 	if err != nil {
 		return nil, fmt.Errorf("could not read version from GOROOT (%v): %v", goroot, err)
 	}
-	if major != 1 || minor < 18 || minor > 20 {
+	if major != 1 || minor < 18 || minor > 21 {
 		// Note: when this gets updated, also update the Go compatibility matrix:
 		// https://github.com/tinygo-org/tinygo-site/blob/dev/content/docs/reference/go-compat-matrix.md
 		return nil, fmt.Errorf("requires go version 1.18 through 1.20, got go%d.%d", major, minor)
diff --git a/src/internal/bytealg/bytealg.go b/src/internal/bytealg/bytealg.go
index a6744c4144..72be9ac587 100644
--- a/src/internal/bytealg/bytealg.go
+++ b/src/internal/bytealg/bytealg.go
@@ -251,3 +251,13 @@ func IndexRabinKarp(s, substr string) int {
 	}
 	return -1
 }
+
+// MakeNoZero makes a slice of length and capacity n without zeroing the bytes.
+// It is the caller's responsibility to ensure uninitialized bytes
+// do not leak to the end user.
+func MakeNoZero(n int) []byte {
+	// Note: this does zero the buffer even though that's not necessary.
+	// For performance reasons we might want to change this (similar to the
+	// malloc function implemented in the runtime).
+	return make([]byte, n)
+}
diff --git a/src/runtime/baremetal.go b/src/runtime/baremetal.go
index a51191bb95..173d0db25e 100644
--- a/src/runtime/baremetal.go
+++ b/src/runtime/baremetal.go
@@ -38,6 +38,8 @@ func growHeap() bool {
 
 //export malloc
 func libc_malloc(size uintptr) unsafe.Pointer {
+	// Note: this zeroes the returned buffer which is not necessary.
+	// The same goes for bytealg.MakeNoZero.
 	return alloc(size, nil)
 }
 
diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index ceb6a2240c..b8be787b54 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -100,3 +100,21 @@ func godebug_setUpdate(update func(string, string)) {
 	// variable changes (for example, via os.Setenv).
 	godebugUpdate = update
 }
+
+//go:linkname godebug_setNewIncNonDefault internal/godebug.setNewIncNonDefault
+func godebug_setNewIncNonDefault(newIncNonDefault func(string) func()) {
+	// Dummy function necessary in Go 1.21.
+}
+
+// Write to the given file descriptor.
+// This is called from internal/godebug starting with Go 1.21, and only seems to
+// be called with the stderr file descriptor.
+func write(fd uintptr, p unsafe.Pointer, n int32) int32 {
+	if fd == 2 { // stderr
+		// Convert to a string, because we know that p won't change during the
+		// call to printstring.
+		printstring(unsafe.String((*byte)(p), n))
+		return n
+	}
+	return 0
+}
diff --git a/src/runtime/runtime_nintendoswitch.go b/src/runtime/runtime_nintendoswitch.go
index f2606023ff..bcfa5151d0 100644
--- a/src/runtime/runtime_nintendoswitch.go
+++ b/src/runtime/runtime_nintendoswitch.go
@@ -105,7 +105,7 @@ func abort() {
 }
 
 //export write
-func write(fd int32, buf *byte, count int) int {
+func libc_write(fd int32, buf *byte, count int) int {
 	// TODO: Proper handling write
 	for i := 0; i < count; i++ {
 		putchar(*buf)
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index cfc9885d7f..37c21ee895 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -5,11 +5,14 @@ type Frames struct {
 }
 
 type Frame struct {
+	PC uintptr
+
+	Func *Func
+
 	Function string
 
 	File string
 	Line int
-	PC   uintptr
 }
 
 func CallersFrames(callers []uintptr) *Frames {