diff --git a/mod/modfile/modfile.go b/mod/modfile/modfile.go
index 7b04ca226..9b28805f1 100644
--- a/mod/modfile/modfile.go
+++ b/mod/modfile/modfile.go
@@ -207,9 +207,13 @@ func parse(modfile []byte, filename string, strict bool) (*File, error) {
 		mf.Module += "@v0"
 	}
 	if mf.Language != nil {
-		if vers := mf.Language.Version; vers != "" && !semver.IsValid(vers) {
+		vers := mf.Language.Version
+		if !semver.IsValid(vers) {
 			return nil, fmt.Errorf("language version %q in %s is not well formed", vers, filename)
 		}
+		if semver.Canonical(vers) != vers {
+			return nil, fmt.Errorf("language version %v in %s is not canonical", vers, filename)
+		}
 	}
 	var versions []module.Version
 	// The main module is always the default for its own major version.
diff --git a/mod/modfile/modfile_test.go b/mod/modfile/modfile_test.go
index 89406e9bf..fe33102ce 100644
--- a/mod/modfile/modfile_test.go
+++ b/mod/modfile/modfile_test.go
@@ -122,6 +122,21 @@ module: "foo.com/bar@v0"
 language: version: "vblah"
 module: "foo.com/bar@v0"`,
 	wantError: `language version "vblah" in module.cue is not well formed`,
+}, {
+	testName: "EmptyLanguageVersion",
+	parse:    Parse,
+	data: `
+language: {}
+module: "foo.com/bar@v0"`,
+	wantError: `language version "" in module.cue is not well formed`,
+}, {
+	testName: "NonCanonicalLanguageVersion",
+	parse:    Parse,
+	data: `
+module: "foo.com/bar@v0"
+language: version: "v0.8"
+`,
+	wantError: `language version v0.8 in module.cue is not canonical`,
 }, {
 	testName: "InvalidDepVersion",
 	parse:    Parse,