diff --git a/nominatim/CMakeLists.txt b/nominatim/CMakeLists.txt
index b391a342..d862b2b3 100644
--- a/nominatim/CMakeLists.txt
+++ b/nominatim/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_executable(nominatim export.c geometry.cpp import.c index.c input.c nominatim.c postgresql.c sprompt.c)
+include(CheckSymbolExists)
 
 CHECK_SYMBOL_EXISTS(bswap_32 "byteswap.h" HAVE_BYTESWAP)
 CHECK_SYMBOL_EXISTS(bswap32 "sys/endian.h" HAVE_SYS_ENDIAN)