diff --git a/CMakeLists.txt b/CMakeLists.txt
index 65ac4bdd4..01865fcf7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -450,7 +450,17 @@ include(CheckCXXSourceCompiles)
 set(CMAKE_REQUIRED_INCLUDES ${LENSFUN_INCLUDE_DIRS})
 set(CMAKE_REQUIRED_LIBRARIES)
 foreach(l ${LENSFUN_LIBRARIES})
-    find_library(_l ${l} PATHS ${LENSFUN_LIBRARY_DIRS} NO_DEFAULT_PATH)
+    if(LENSFUN_LIBRARY_DIRS)
+        # the NO_DEFAULT_PATH is to make sure we find the lensfun version we
+        # want, and not the system's one (e.g. if we have a custom version
+        # installed in a non-standard location)
+        find_library(_l ${l} PATHS ${LENSFUN_LIBRARY_DIRS} NO_DEFAULT_PATH)
+    else()
+        # LENSFUN_LIBRARY_DIRS can be empty if lensfun is installed in the
+        # default path. In this case, adding NO_DEFAULT_PATH would make
+        # find_library fail...
+        find_library(_l ${l})
+    endif()
     set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} ${_l})
 endforeach()
 check_cxx_source_compiles(