diff --git a/CMakeLists.txt b/CMakeLists.txt
index c81796e5..d89f53ee 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -185,7 +185,7 @@ if (EXISTS .gitignore)
     string(REPLACE "*" ".*" line "${line}")
     set(ignored_files ${ignored_files} "${line}$" "${line}/")
   endforeach ()
-  set(ignored_files ${ignored_files} /.git /breathe /format-benchmark)
+  set(ignored_files ${ignored_files} /.git /breathe /format-benchmark /sphinx)
 
   set(CPACK_SOURCE_GENERATOR ZIP)
   set(CPACK_SOURCE_IGNORE_FILES ${ignored_files})