diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
index 933f582a2e6..badaf1bf158 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java
@@ -1407,9 +1407,6 @@ public class Types {
 
                     Map<Symbol,Type> tMap = new HashMap<>();
                     for (Type ti : interfaces(t)) {
-                        if (tMap.containsKey(ti)) {
-                            throw new AssertionError("Malformed intersection");
-                        }
                         tMap.put(ti.tsym, ti);
                     }
                     for (Type si : interfaces(s)) {
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
index 513122317f1..aa480afa3ba 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
@@ -5116,11 +5116,11 @@ public class Attr extends JCTree.Visitor {
     }
 
     Type checkIntersection(JCTree tree, List<JCExpression> bounds) {
-        Set<Type> boundSet = new HashSet<>();
+        Set<Symbol> boundSet = new HashSet<>();
         if (bounds.nonEmpty()) {
             // accept class or interface or typevar as first bound.
             bounds.head.type = checkBase(bounds.head.type, bounds.head, env, false, false, false);
-            boundSet.add(types.erasure(bounds.head.type));
+            boundSet.add(types.erasure(bounds.head.type).tsym);
             if (bounds.head.type.isErroneous()) {
                 return bounds.head.type;
             }
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
index e1dbbabb8f7..893ba5699e6 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
@@ -2872,11 +2872,11 @@ public class Check {
     /** Enter interface into into set.
      *  If it existed already, issue a "repeated interface" error.
      */
-    void checkNotRepeated(DiagnosticPosition pos, Type it, Set<Type> its) {
-        if (its.contains(it))
+    void checkNotRepeated(DiagnosticPosition pos, Type it, Set<Symbol> its) {
+        if (its.contains(it.tsym))
             log.error(pos, Errors.RepeatedInterface);
         else {
-            its.add(it);
+            its.add(it.tsym);
         }
     }
 
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java
index cd767f7db3b..ce6eca795fd 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java
@@ -845,7 +845,7 @@ public class TypeEnter implements Completer {
 
             fillPermits(tree, baseEnv);
 
-            Set<Type> interfaceSet = new HashSet<>();
+            Set<Symbol> interfaceSet = new HashSet<>();
 
             for (JCExpression iface : tree.implementing) {
                 Type it = iface.type;