diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 2567e403..c9cd17e7 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -190,8 +190,10 @@ C++:
   - cpp
   primary_extension: .cpp
   extensions:
+  - .C
   - .c++
   - .cxx
+  - .H
   - .h++
   - .hh
   - .hxx