diff --git a/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs b/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs
index 6b5d0bbf37..3574b831ec 100644
--- a/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs
+++ b/ICSharpCode.NRefactory.CSharp/Completion/CSharpCompletionEngineBase.cs
@@ -349,8 +349,9 @@ namespace ICSharpCode.NRefactory.CSharp.Completion
 							if (nextCh == '/') {
 								i++;
 								IsInSingleComment = true;
+								IsInPreprocessorDirective = false;
 							}
-							if (nextCh == '*')
+							if (nextCh == '*' && !IsInPreprocessorDirective)
 								IsInMultiLineComment = true;
 							break;
 						case '*':
diff --git a/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/PreProcessorTests.cs b/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/PreProcessorTests.cs
index 68e3a56428..e7dbf37daf 100644
--- a/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/PreProcessorTests.cs
+++ b/ICSharpCode.NRefactory.Tests/CSharp/CodeCompletion/PreProcessorTests.cs
@@ -90,5 +90,16 @@ namespace ICSharpCode.NRefactory.CSharp.CodeCompletion
 			provider = CodeCompletionBugTests.CreateProvider (@"$#if TRUE && $", true);
 			Assert.IsNotNull (provider.Find ("DEBUG"), "define 'DEBUG' not found.");
 		}	
+
+
+		/// <summary>
+		/// Bug 10294 - Comments in preprocessor directives are not handler correctly
+		/// </summary>
+		[Test]
+		public void TestBug10294 ()
+		{
+			var provider = CodeCompletionBugTests.CreateProvider (@"$#if TRUE // D$",true);
+			Assert.IsTrue (provider == null || provider.Count == 0);
+		}
 	}
 }