diff --git a/src/pkg/crypto/sha1/sha1block_decl.go b/src/pkg/crypto/sha1/sha1block_decl.go
index 3512a582991..4cb157fff6d 100644
--- a/src/pkg/crypto/sha1/sha1block_decl.go
+++ b/src/pkg/crypto/sha1/sha1block_decl.go
@@ -6,4 +6,6 @@
 
 package sha1
 
+//go:noescape
+
 func block(dig *digest, p []byte)