diff --git a/src/output.cpp b/src/output.cpp
index f36021a..105578b 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -128,7 +128,7 @@ void json_all(const std::vector<std::vector<search::match>> &matches_all)
         }
     }
 
-    std::cout << json.dump() << '\n';
+    cout << json.dump() << '\n';
 }
 
 } // namespace epubgrep::output
diff --git a/src/output.hpp b/src/output.hpp
index 5f25148..e578103 100644
--- a/src/output.hpp
+++ b/src/output.hpp
@@ -29,6 +29,7 @@ namespace epubgrep::output
 void print_matches(const std::vector<search::match> &matches,
                    const options::options &opts, bool single_file);
 
+//! Print all matches as JSON.
 void json_all(const std::vector<std::vector<search::match>> &matches_all);
 
 } // namespace epubgrep::output