diff --git a/Source/CTest/CMakeLists.txt b/Source/CTest/CMakeLists.txt
index e969dc8f8..c248f7dc3 100644
--- a/Source/CTest/CMakeLists.txt
+++ b/Source/CTest/CMakeLists.txt
@@ -8,7 +8,7 @@ IF(CMAKE_SYSTEM MATCHES "AIX.*")
   ENDIF(NOT CMAKE_COMPILER_IS_GNUCXX)
 ENDIF(CMAKE_SYSTEM MATCHES "AIX.*")
 
-SET(HAVE_LIBCRYPTO 0 CACHE INTERNAL)
+SET(HAVE_LIBCRYPTO 0 CACHE INTERNAL "")
 
 IF(CMAKE_BUILD_WITH_CURL)
   SET(CMAKE_LIBRARY CMakeLib)