diff --git a/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java b/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
index 7770f6ad4376..8bd66654790f 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/psi/RegExpGroup.java
@@ -19,6 +19,8 @@ import org.jetbrains.annotations.Nullable;
 
 public interface RegExpGroup extends RegExpAtom {
     boolean isCapturing();
+  
+    boolean isSimple();
 
     @Nullable
     RegExpPattern getPattern();
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java b/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
index 9b8fa67ece98..368dd0fd7bb4 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/psi/impl/RegExpGroupImpl.java
@@ -37,6 +37,11 @@ public class RegExpGroupImpl extends RegExpElementImpl implements RegExpGroup {
         return node != null && node.getElementType() == RegExpTT.GROUP_BEGIN;
     }
 
+    public boolean isSimple() {
+        final ASTNode node = getNode().getFirstChildNode();
+        return node != null && (node.getElementType() == RegExpTT.GROUP_BEGIN || node.getElementType() == RegExpTT.NON_CAPT_GROUP);
+    }
+
     public RegExpPattern getPattern() {
         final ASTNode node = getNode().findChildByType(RegExpElementTypes.PATTERN);
         return node != null ? (RegExpPattern)node.getPsi() : null;
diff --git a/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java b/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
index 52307d1cd58d..4ddc4fbb0855 100644
--- a/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
+++ b/RegExpSupport/src/org/intellij/lang/regexp/validation/RegExpAnnotator.java
@@ -155,7 +155,12 @@ public final class RegExpAnnotator extends RegExpElementVisitor implements Annot
             } else if (branches.length == 1) {
                 final RegExpAtom[] atoms = branches[0].getAtoms();
                 if (atoms.length == 1 && atoms[0] instanceof RegExpGroup) {
-                    myHolder.createWarningAnnotation(group, "Redundant group nesting");
+                  if (group.isSimple()) {
+                    final RegExpGroup innerGroup = (RegExpGroup)atoms[0];
+                    if (group.isCapturing() == innerGroup.isCapturing()) {
+                      myHolder.createWarningAnnotation(group, "Redundant group nesting");                      
+                    }
+                  }
                 }
             }
         }
diff --git a/RegExpSupport/testData/RETest.xml b/RegExpSupport/testData/RETest.xml
index e0c7c3163d86..2316463a0863 100644
--- a/RegExpSupport/testData/RETest.xml
+++ b/RegExpSupport/testData/RETest.xml
@@ -990,4 +990,11 @@
       <expected>OK</expected>
     </test>
   </bug>
+  
+  <bug id="IDEA-52291">
+    <test>
+      <pattern>(^|\.)\*(?=(\.|$))</pattern>
+      <expected>OK</expected>
+    </test>
+  </bug>
 </tests>