diff --git a/CMakeLists.txt b/CMakeLists.txt
index a93a8308c8..141cea0cce 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -200,18 +200,18 @@ if(NOT IGC__IGC_TARGETS)
     if(UNIX)
         # on Unix-like use pkg-config
         find_package(PkgConfig)
-        if(IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
+        if(DEFINED IGC_DIR AND IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
             set(ENV{PKG_CONFIG_PATH} "${IGC_DIR}/lib/pkgconfig/")
         endif()
         pkg_check_modules(IGDRCL__IGC igc-opencl)
-        if(IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
+        if(DEFINED IGC_DIR AND IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
             unset(ENV{PKG_CONFIG_PATH})
             set(IGDRCL__IGC_LIBRARY_PATH "${IGC_DIR}/lib/")
             set(ENV{LD_LIBRARY_PATH} "${IGDRCL__IGC_LIBRARY_PATH}")
         endif()
 
         if(IGDRCL__IGC_FOUND)
-            if(IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
+            if(DEFINED IGC_DIR AND IS_DIRECTORY "${IGC_DIR}/lib/pkgconfig/")
                 string(REPLACE "${IGDRCL__IGC_INCLUDEDIR}" "${IGC_DIR}/include/igc" IGDRCL__IGC_INCLUDE_DIRS "${IGDRCL__IGC_INCLUDE_DIRS}")
             endif()