diff --git a/CMakeModules/FindHelpers.cmake b/CMakeModules/FindHelpers.cmake
index a9d66a553..36003191c 100644
--- a/CMakeModules/FindHelpers.cmake
+++ b/CMakeModules/FindHelpers.cmake
@@ -273,9 +273,14 @@ MACRO(FIND_PACKAGE_HELPER NAME INCLUDE)
   ENDIF()
 
   # Append environment variables XXX_DIR
-  LIST(APPEND _LIBRARY_PATHS
-    $ENV{${_UPNAME}_DIR}/lib${LIB_SUFFIX}
-    $ENV{${_UPNAME_FIXED}_DIR}/lib${LIB_SUFFIX})
+  IF(DEFINED ENV{${_UPNAME}_DIR})
+    LIST(APPEND _LIBRARY_PATHS
+      $ENV{${_UPNAME}_DIR}/lib${LIB_SUFFIX})
+  ENDIF()
+  IF(DEFINED ENV{${_UPNAME_FIXED}_DIR})
+    LIST(APPEND _LIBRARY_PATHS
+      $ENV{${_UPNAME_FIXED}_DIR}/lib${LIB_SUFFIX})
+  ENDIF()
 
   IF(UNIX AND NOT DEFINED ENV{${_UPNAME_FIXED}_ROOT})
     SET(_UNIX_LIBRARY_PATHS)
@@ -322,15 +327,30 @@ MACRO(FIND_PACKAGE_HELPER NAME INCLUDE)
   LIST(REMOVE_DUPLICATES _DEBUG_LIBRARIES)
 
   # Search for release library
-  FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_RELEASE
-    NAMES
-    ${_RELEASE_LIBRARIES}
-    HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
-    PATHS
-    ${_LIBRARY_PATHS}
-    ${_UNIX_LIBRARY_PATHS}
-    NO_CMAKE_SYSTEM_PATH
-  )
+  IF(DEFINED ENV{${_UPNAME_FIXED}_ROOT})
+    FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_RELEASE
+      NAMES
+      ${_RELEASE_LIBRARIES}
+      HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
+      PATHS
+      ${_LIBRARY_PATHS}
+      ${_UNIX_LIBRARY_PATHS}
+      NO_CMAKE_PATH 
+      NO_CMAKE_SYSTEM_PATH
+      NO_CMAKE_ENVIRONMENT_PATH
+      NO_SYSTEM_ENVIRONMENT_PATH
+    )
+  ELSE()
+    FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_RELEASE
+      NAMES
+      ${_RELEASE_LIBRARIES}
+      HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
+      PATHS
+      ${_LIBRARY_PATHS}
+      ${_UNIX_LIBRARY_PATHS}
+      NO_CMAKE_SYSTEM_PATH
+    )
+  ENDIF()
 
   IF(_IS_VERBOSE)
     IF(${_UPNAME_FIXED}_LIBRARY_RELEASE)
@@ -341,15 +361,30 @@ MACRO(FIND_PACKAGE_HELPER NAME INCLUDE)
   ENDIF()
 
   # Search for debug library
-  FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_DEBUG
-    NAMES
-    ${_DEBUG_LIBRARIES}
-    HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
-    PATHS
-    ${_LIBRARY_PATHS}
-    ${_UNIX_LIBRARY_PATHS}
-    NO_CMAKE_SYSTEM_PATH
-  )
+  IF(DEFINED ENV{${_UPNAME_FIXED}_ROOT})
+    FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_DEBUG
+      NAMES
+      ${_DEBUG_LIBRARIES}
+      HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
+      PATHS
+      ${_LIBRARY_PATHS}
+      ${_UNIX_LIBRARY_PATHS}
+      NO_CMAKE_PATH 
+      NO_CMAKE_SYSTEM_PATH
+      NO_CMAKE_ENVIRONMENT_PATH
+      NO_SYSTEM_ENVIRONMENT_PATH
+    )
+  ELSE()
+    FIND_LIBRARY(${_UPNAME_FIXED}_LIBRARY_DEBUG
+      NAMES
+      ${_DEBUG_LIBRARIES}
+      HINTS ${PKG_${_NAME_FIXED}_LIBRARY_DIRS}
+      PATHS
+      ${_LIBRARY_PATHS}
+      ${_UNIX_LIBRARY_PATHS}
+      NO_CMAKE_SYSTEM_PATH
+    )
+  ENDIF()
 
   IF(_IS_VERBOSE)
     IF(${_UPNAME_FIXED}_LIBRARY_DEBUG)