diff --git a/Modules/DeployQt4.cmake b/Modules/DeployQt4.cmake
index ef8dd1f1a..4bf1b6c4b 100644
--- a/Modules/DeployQt4.cmake
+++ b/Modules/DeployQt4.cmake
@@ -225,9 +225,11 @@ function(install_qt4_plugin plugin executable copy installed_plugin_path_var)
                 else()
                         string(TOUPPER "QT_${plugin}_PLUGIN" plugin_var)
                 endif()
-                set(plugin_release "${${plugin_var}_RELEASE}")
-                set(plugin_debug "${${plugin_var}_DEBUG}")
-                if(NOT EXISTS "${plugin_release}" AND NOT EXISTS "${plugin_debug}")
+                set(plugin_release_var "${plugin_var}_RELEASE")
+                set(plugin_debug_var "${plugin_var}_DEBUG")
+                set(plugin_release "${${plugin_release_var}}")
+                set(plugin_debug "${${plugin_debug_var}}")
+                if(DEFINED "${plugin_release_var}" AND DEFINED "${plugin_debug_var}" AND NOT EXISTS "${plugin_release}" AND NOT EXISTS "${plugin_debug}")
                         message(WARNING "Qt plugin \"${plugin}\" not recognized or found.")
                 endif()
                 install_qt4_plugin_path("${plugin_release}" "${executable}" "${copy}" "${installed_plugin_path_var}" "${plugins_dir}" "${component}" "Release|RelWithDebInfo|MinSizeRel")