diff --git a/include/searcher.h b/include/searcher.h
index 9c005825..2d3a58f5 100644
--- a/include/searcher.h
+++ b/include/searcher.h
@@ -89,7 +89,7 @@ class Searcher
    * @param resultEnd the end offset of the search results (used for pagination).
    * @param verbose print some info on stdout if true.
    */
-  void search(std::string& search,
+  void search(const std::string& search,
               unsigned int resultStart,
               unsigned int resultEnd,
               const bool verbose = false);
diff --git a/src/searcher.cpp b/src/searcher.cpp
index 6802d663..fb5eca13 100644
--- a/src/searcher.cpp
+++ b/src/searcher.cpp
@@ -97,7 +97,7 @@ Reader* Searcher::get_reader(int readerIndex)
 }
 
 /* Search strings in the database */
-void Searcher::search(std::string& search,
+void Searcher::search(const std::string& search,
                       unsigned int resultStart,
                       unsigned int resultEnd,
                       const bool verbose)