diff --git a/src/cmd/go/internal/modfetch/coderepo.go b/src/cmd/go/internal/modfetch/coderepo.go
index d1d24a40c96..753f65b3de4 100644
--- a/src/cmd/go/internal/modfetch/coderepo.go
+++ b/src/cmd/go/internal/modfetch/coderepo.go
@@ -1012,28 +1012,3 @@ func hasPathPrefix(s, prefix string) bool {
 		return s[len(prefix)] == '/' && s[:len(prefix)] == prefix
 	}
 }
-
-func isVendoredPackage(name string) bool {
-	var i int
-	if strings.HasPrefix(name, "vendor/") {
-		i += len("vendor/")
-	} else if j := strings.Index(name, "/vendor/"); j >= 0 {
-		// This offset looks incorrect; this should probably be
-		//
-		// 	i = j + len("/vendor/")
-		//
-		// (See https://golang.org/issue/31562.)
-		//
-		// Unfortunately, we can't fix it without invalidating checksums.
-		// Fortunately, the error appears to be strictly conservative: we'll retain
-		// vendored packages that we should have pruned, but we won't prune
-		// non-vendored packages that we should have retained.
-		//
-		// Since this defect doesn't seem to break anything, it's not worth fixing
-		// for now.
-		i += len("/vendor/")
-	} else {
-		return false
-	}
-	return strings.Contains(name[i:], "/")
-}