diff --git a/utils.cmake b/utils.cmake
index 763c477..9ae6911 100644
--- a/utils.cmake
+++ b/utils.cmake
@@ -45,12 +45,12 @@ function(are_paths_equal lhs rhs out_var)
 endfunction()
 
 function(compute_install_dir)
-    cmake_parse_arguments(arg "NO_64BIT_SUFFIX;ROOT" "IS_MULTI_CONFIG;BIN_DIR;LIB_DIR;INCLUDE_DIR;QML_DIR;DATA_DIR;INFO_DIR;MAN_DIR;DOC_DIR;LOCALE_DIR" "" ${ARGN})
+    cmake_parse_arguments(arg "APPEND_64BIT_SUFFIX;ROOT" "IS_MULTI_CONFIG;BIN_DIR;LIB_DIR;INCLUDE_DIR;QML_DIR;DATA_DIR;INFO_DIR;MAN_DIR;DOC_DIR;LOCALE_DIR" "" ${ARGN})
     if(arg_UNPARSED_ARGUMENTS)
         message(AUTHOR_WARNING "compute_install_dir: Unrecognized arguments: ${arg_UNPARSED_ARGUMENTS}")
     endif()
     set(__dir_suffix "")
-    if(CMAKE_SIZEOF_VOID_P EQUAL 8 AND NOT arg_NO_64BIT_SUFFIX)
+    if(CMAKE_SIZEOF_VOID_P EQUAL 8 AND arg_APPEND_64BIT_SUFFIX)
         set(__dir_suffix "64")
     endif()
     include(GNUInstallDirs)