Index: include-fixer/IncludeFixer.cpp
===================================================================
--- include-fixer/IncludeFixer.cpp
+++ include-fixer/IncludeFixer.cpp
@@ -86,6 +86,15 @@
     if (getCompilerInstance().getSema().isSFINAEContext())
       return clang::TypoCorrection();
 
+    // We currently ignore the unidentified symbol which is not from the
+    // main file.
+    //
+    // FIXME: Add the missing header to the header file where the symbol comes
+    // from.
+    if (!getCompilerInstance().getSourceManager().isWrittenInMainFile(
+            Typo.getLoc()))
+      return clang::TypoCorrection();
+
     std::string TypoScopeString;
     if (S) {
       // FIXME: Currently we only use namespace contexts. Use other context
Index: unittests/include-fixer/IncludeFixerTest.cpp
===================================================================
--- unittests/include-fixer/IncludeFixerTest.cpp
+++ unittests/include-fixer/IncludeFixerTest.cpp
@@ -44,6 +44,8 @@
                               llvm::MemoryBuffer::getMemBuffer("\n"));
   InMemoryFileSystem->addFile("dir/otherdir/qux.h", 0,
                               llvm::MemoryBuffer::getMemBuffer("\n"));
+  InMemoryFileSystem->addFile("header.h", 0,
+                              llvm::MemoryBuffer::getMemBuffer("bar b;"));
   return Invocation.run();
 }
 
@@ -186,6 +188,11 @@
             runIncludeFixer("int test = a::b::Green;\n"));
 }
 
+TEST(IncludeFixer, IgnoreSymbolFromHeader) {
+  std::string Code = "#include \"header.h\"";
+  EXPECT_EQ(Code, runIncludeFixer(Code));
+}
+
 // FIXME: add test cases for inserting and sorting multiple headers when
 // include-fixer supports multiple headers insertion.
 TEST(IncludeFixer, InsertAndSortSingleHeader) {