diff --git a/FindMyxlib.cmake b/FindMyxlib.cmake
index 818aa23..c78c361 100644
--- a/FindMyxlib.cmake
+++ b/FindMyxlib.cmake
@@ -4,11 +4,11 @@ if(NOT MYXLIB_IS_EXTERNAL_PROJECT)
   set(MYXLIB_LIBRARY_DIR "" CACHE PATH "The path to the library of an myxlib installation")
 
   set(_search_paths "")
-  if(EXISTS MYXLIB_INCLUDE_DIR)
+  if(MYXLIB_INCLUDE_DIR AND EXISTS ${MYXLIB_INCLUDE_DIR})
     list(APPEND _search_paths ${MYXLIB_INCLUDE_DIR})
   endif()
-  if(EXISTS MYXLIB_PREFIX)
-    list(APPEND _search_paths ${MYXLIB_PREFIX}/include)
+  if(MYXLIB_PREFIX AND EXISTS ${MYXLIB_PREFIX})
+    list(APPEND _search_paths "${MYXLIB_PREFIX}/include")
   endif()
   find_path(
     MYXLIB_INCLUDE_DIRS
@@ -16,11 +16,11 @@ if(NOT MYXLIB_IS_EXTERNAL_PROJECT)
     PATHS ${_search_paths})
 
   set(_search_paths "")
-  if(EXISTS MYXLIB_LIBRARY_DIR)
+  if(MYXLIB_LIBRARY_DIR AND EXISTS ${MYXLIB_LIBRARY_DIR})
     list(APPEND _search_paths ${MYXLIB_LIBRARY_DIR})
   endif()
-  if(EXISTS MYXLIB_PREFIX)
-    list(APPEND _search_paths ${MYXLIB_PREFIX}/lib)
+  if(MYXLIB_PREFIX AND EXISTS ${MYXLIB_PREFIX})
+    list(APPEND _search_paths "${MYXLIB_PREFIX}/lib")
   endif()
   find_library(
     MYXLIB_QT_LIBRARIES