Index: externals/cmake-modules/Findcryptopp.cmake
--- externals/cmake-modules/Findcryptopp.cmake.orig
+++ externals/cmake-modules/Findcryptopp.cmake
@@ -1,4 +1,5 @@
 if(NOT CRYPTOPP_FOUND)
+    include(FindPkgConfig)
     pkg_search_module(CRYPTOPP_TMP crypto++ cryptopp)
 
     find_path(CRYPTOPP_INCLUDE_DIRS NAMES cryptlib.h
