diff --git a/misc/genstd/genstd.go b/misc/genstd/genstd.go
index 3dd38214595..f3656b5c0c5 100644
--- a/misc/genstd/genstd.go
+++ b/misc/genstd/genstd.go
@@ -119,13 +119,25 @@ func walkStdlibs(stdlibsPath string) ([]*pkgData, error) {
 			return nil
 		}
 
-		// skip non-source and test files.
+		// skip non-source files.
 		ext := filepath.Ext(fpath)
 		if (ext != ".go" && ext != ".gno") ||
 			strings.HasSuffix(fpath, ".gen.go") {
 			return nil
 		}
 
+		fs := token.NewFileSet()
+		f, err := parser.ParseFile(fs, fpath, nil, parser.SkipObjectResolution)
+		if err != nil {
+			return err
+		}
+
+		// skip external test files
+		noExt := fpath[:len(fpath)-len(ext)]
+		if strings.HasSuffix(noExt, "_test") && strings.HasSuffix(f.Name.Name, "_test") {
+			return nil
+		}
+
 		dir := filepath.Dir(fpath)
 		var pkg *pkgData
 		// if we've already been in this directory in a previous file, it must
@@ -141,11 +153,6 @@ func walkStdlibs(stdlibsPath string) ([]*pkgData, error) {
 		} else {
 			pkg = pkgs[len(pkgs)-1]
 		}
-		fs := token.NewFileSet()
-		f, err := parser.ParseFile(fs, fpath, nil, parser.SkipObjectResolution)
-		if err != nil {
-			return err
-		}
 
 		if ext == ".go" {
 			// keep track of exported function declarations.