diff --git a/xml/impl/src/com/intellij/html/impl/Html5CustomAttributeDescriptorsProvider.java b/xml/impl/src/com/intellij/html/impl/Html5CustomAttributeDescriptorsProvider.java
index fc9fe289efed..1d9533eef727 100644
--- a/xml/impl/src/com/intellij/html/impl/Html5CustomAttributeDescriptorsProvider.java
+++ b/xml/impl/src/com/intellij/html/impl/Html5CustomAttributeDescriptorsProvider.java
@@ -91,7 +91,7 @@ public class Html5CustomAttributeDescriptorsProvider implements XmlAttributeDesc
 
   @Override
   public XmlAttributeDescriptor getAttributeDescriptor(String attributeName, XmlTag context) {
-    if (context != null && HtmlUtil.isHtml5Context(context) && HtmlUtil.isCustomHtml5Attribute(attributeName)) {
+    if (context != null && HtmlUtil.isCustomHtml5Attribute(attributeName) && HtmlUtil.tagHasHtml5Schema(context)) {
       return new AnyXmlAttributeDescriptor(attributeName);
     }
     return null;
diff --git a/xml/xml-psi-impl/src/com/intellij/xml/util/HtmlUtil.java b/xml/xml-psi-impl/src/com/intellij/xml/util/HtmlUtil.java
index e7c9168d3e36..02ac9f070abf 100644
--- a/xml/xml-psi-impl/src/com/intellij/xml/util/HtmlUtil.java
+++ b/xml/xml-psi-impl/src/com/intellij/xml/util/HtmlUtil.java
@@ -26,6 +26,7 @@ import com.intellij.lang.xhtml.XHTMLLanguage;
 import com.intellij.openapi.Disposable;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.openapi.util.Comparing;
 import com.intellij.openapi.util.Disposer;
 import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.registry.Registry;
@@ -497,6 +498,18 @@ public class HtmlUtil {
     return "meta.rnc".equals(name);
   }
 
+  public static boolean tagHasHtml5Schema(@NotNull XmlTag context) {
+    XmlElementDescriptor descriptor = context.getDescriptor();
+    if (descriptor != null) {
+      XmlNSDescriptor nsDescriptor = descriptor.getNSDescriptor();
+      XmlFile descriptorFile = nsDescriptor.getDescriptorFile();
+      String descriptorPath = descriptorFile != null ? descriptorFile.getVirtualFile().getPath() : null;
+      return Comparing.equal(Html5SchemaProvider.getHtml5SchemaLocation(), descriptorPath) ||
+             Comparing.equal(Html5SchemaProvider.getXhtml5SchemaLocation(), descriptorPath);
+    }
+    return false;
+  }
+
   private static class TerminateException extends RuntimeException {
     private static final TerminateException INSTANCE = new TerminateException();
   }