diff --git a/src/gn/source_file.cc b/src/gn/source_file.cc
index 89c8cf0..52066d7 100644
--- a/src/gn/source_file.cc
+++ b/src/gn/source_file.cc
@@ -23,7 +23,8 @@
 
 SourceFile::Type GetSourceFileType(const std::string& file) {
   std::string_view extension = FindExtension(&file);
-  if (extension == "cc" || extension == "cpp" || extension == "cxx")
+  if (extension == "cc" || extension == "cpp" || extension == "cxx" ||
+      extension == "c++")
     return SourceFile::SOURCE_CPP;
   if (extension == "h" || extension == "hpp" || extension == "hxx" ||
       extension == "hh" || extension == "inc" || extension == "ipp" ||