diff --git a/package.json b/package.json
index 79fec05d..62abca4c 100644
--- a/package.json
+++ b/package.json
@@ -9,7 +9,7 @@
     "resolve": "^1.4.0",
     "tslib": "^1.8.0",
     "tsutils": "^3.0.0",
-    "tsutils-etc": "^1.0.0"
+    "tsutils-etc": "^1.1.0"
   },
   "description": "TSLint rules for RxJS",
   "devDependencies": {
diff --git a/source/rules/rxjsNoSubclassRule.ts b/source/rules/rxjsNoSubclassRule.ts
index 42ca1231..00f9692d 100644
--- a/source/rules/rxjsNoSubclassRule.ts
+++ b/source/rules/rxjsNoSubclassRule.ts
@@ -56,7 +56,10 @@ export class Rule extends Lint.Rules.TypedRule {
                 if (heritageClause.token === ts.SyntaxKind.ExtendsKeyword) {
                     heritageClause.types.forEach(heritageType => {
                         const type = typeChecker.getTypeAtLocation(heritageType);
-                        if (couldBeNames.some(name => couldBeType(type, name))) {
+                        if (couldBeNames.some(name => couldBeType(type, name, {
+                            name: /rxjs/,
+                            typeChecker
+                        }))) {
                             failures.push(new Lint.RuleFailure(
                                 sourceFile,
                                 heritageType.getStart(),
diff --git a/test/v6/fixtures/issues/87/fixture.ts.lint b/test/v6/fixtures/issues/87/fixture.ts.lint
index 488fd7a0..3e59d343 100644
--- a/test/v6/fixtures/issues/87/fixture.ts.lint
+++ b/test/v6/fixtures/issues/87/fixture.ts.lint
@@ -1,8 +1,5 @@
-class Observable<T> {
-    t: T;
-}
+class Observable<T> { t: T; }
 
-class StringObservable extends Observable<string> {
-}
+class StringObservable extends Observable<string> {}
 
 [no-subclass]: Subclassing RxJS classes is forbidden
diff --git a/yarn.lock b/yarn.lock
index f8040594..d0389083 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1540,10 +1540,10 @@ tslint@^5.1.0:
     tslib "^1.8.0"
     tsutils "^2.27.2"
 
-tsutils-etc@^1.0.0:
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/tsutils-etc/-/tsutils-etc-1.0.1.tgz#2114f1b41a1d7ad5498690f011a18fa989ebffad"
-  integrity sha512-Yp6RQzPfxuZNjw/tHYdr+QRHtoPX2Al+9UmydyMidGqKt3Y13lJhryLUNPxYce5Y8KQ0Q6qn2MLJIxwL48GBWg==
+tsutils-etc@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/tsutils-etc/-/tsutils-etc-1.1.0.tgz#82ce1c92da29e07d3cde95692d5c5e8dbdc92fd0"
+  integrity sha512-pJlLtLmQPUyGHqY/Pq6EGnpGmQCnnTDZetQ7eWkeQ5xaw4GtfcR1Zt7HMKFHGDDp53HzQfbqQ+7ps6iJbfa9Hw==
 
 tsutils@^2.27.2:
   version "2.29.0"