diff --git a/lib/linter/linter.js b/lib/linter/linter.js
index 410c07fee51..4e07a25751e 100644
--- a/lib/linter/linter.js
+++ b/lib/linter/linter.js
@@ -626,7 +626,7 @@ function analyzeScope(ast, parserOptions, visitorKeys) {
         ignoreEval: true,
         nodejsScope: ecmaFeatures.globalReturn,
         impliedStrict: ecmaFeatures.impliedStrict,
-        ecmaVersion,
+        ecmaVersion: typeof ecmaVersion === "number" ? ecmaVersion : 6,
         sourceType: parserOptions.sourceType || "script",
         childVisitorKeys: visitorKeys || evk.KEYS,
         fallback: Traverser.getKeys
diff --git a/tests/lib/linter/linter.js b/tests/lib/linter/linter.js
index c2bb5fdd746..24dc4de43ce 100644
--- a/tests/lib/linter/linter.js
+++ b/tests/lib/linter/linter.js
@@ -4137,9 +4137,28 @@ var a = "test2";
                         blockScope = context.getScope();
                     }
                 }));
+                linter.defineParser("custom-parser", {
+                    parse: (...args) => espree.parse(...args)
+                });
+
+                // Use standard parser
+                linter.verify("{}", {
+                    rules: { "block-scope": 2 },
+                    parserOptions: { ecmaVersion: "latest" }
+                });
+
+                assert.strictEqual(blockScope.type, "block");
+
+                linter.verify("{}", {
+                    rules: { "block-scope": 2 },
+                    parserOptions: {} // ecmaVersion defaults to 5
+                });
+                assert.strictEqual(blockScope.type, "global");
 
+                // Use custom parser
                 linter.verify("{}", {
                     rules: { "block-scope": 2 },
+                    parser: "custom-parser",
                     parserOptions: { ecmaVersion: "latest" }
                 });
 
@@ -4147,6 +4166,7 @@ var a = "test2";
 
                 linter.verify("{}", {
                     rules: { "block-scope": 2 },
+                    parser: "custom-parser",
                     parserOptions: {} // ecmaVersion defaults to 5
                 });
                 assert.strictEqual(blockScope.type, "global");