diff --git a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectUtils.kt b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectUtils.kt
index 0118623b5a3..94804e3b792 100644
--- a/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectUtils.kt
+++ b/js/js.inliner/src/org/jetbrains/kotlin/js/inline/util/collectUtils.kt
@@ -106,9 +106,9 @@ fun collectDefinedNames(scope: JsNode): Set<JsName> {
             super.visitExpressionStatement(x)
         }
 
-        override fun visitBreak(x: JsBreak) {
-            x.label?.name?.let { names += it }
-            super.visitBreak(x)
+        override fun visitLabel(x: JsLabel) {
+            x.name?.let { names += it }
+            super.visitLabel(x)
         }
 
         override fun visitCatch(x: JsCatch) {
@@ -141,9 +141,9 @@ fun collectDefinedNamesInAllScopes(scope: JsNode): Set<JsName> {
             x.name?.let { names += it }
         }
 
-        override fun visitBreak(x: JsBreak) {
-            x.label?.name?.let { names += it }
-            super.visitBreak(x)
+        override fun visitLabel(x: JsLabel) {
+            x.name?.let { names += it }
+            super.visitLabel(x)
         }
 
         override fun visitCatch(x: JsCatch) {
diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/translate/general/Translation.java b/js/js.translator/src/org/jetbrains/kotlin/js/translate/general/Translation.java
index 87af4512241..15a308db984 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/translate/general/Translation.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/translate/general/Translation.java
@@ -337,6 +337,7 @@ public final class Translation {
 
                 JsProgramFragment fragment = staticContext.getFragment();
                 for (String tag : staticContext.getInlineFunctionTags()) {
+                    assert !inlineFunctionTagMap.containsKey(tag) : "Duplicate inline function tag found: '" + tag + "'";
                     inlineFunctionTagMap.put(tag, unit);
                 }
                 NormalizeImportTagsKt.normalizeImportTags(fragment);
@@ -349,6 +350,7 @@ public final class Translation {
                 byte[] headerData = ((TranslationUnit.BinaryAst) unit).getHeader();
                 JsAstProtoBuf.Header h = JsAstProtoBuf.Header.parseFrom(CodedInputStream.newInstance(headerData));
                 for (String tag : h.getInlineFunctionTagsList()) {
+                    assert !inlineFunctionTagMap.containsKey(tag) : "Duplicate inline function tag found: '" + tag + "'";
                     inlineFunctionTagMap.put(tag, unit);
                 }
             }