diff --git a/Modules/GenerateExportHeader.cmake b/Modules/GenerateExportHeader.cmake
index 7df274e4f..781b6e7d4 100644
--- a/Modules/GenerateExportHeader.cmake
+++ b/Modules/GenerateExportHeader.cmake
@@ -298,7 +298,7 @@ macro(_DO_GENERATE_EXPORT_HEADER TARGET_LIBRARY)
     set(EXPORT_MACRO_NAME ${_GEH_PREFIX_NAME}${_GEH_EXPORT_MACRO_NAME})
   endif()
   if(_GEH_EXPORT_FILE_NAME)
-    if(IS_ABSOLUTE _GEH_EXPORT_FILE_NAME)
+    if(IS_ABSOLUTE ${_GEH_EXPORT_FILE_NAME})
       set(EXPORT_FILE_NAME ${_GEH_EXPORT_FILE_NAME})
     else()
       set(EXPORT_FILE_NAME "${CMAKE_CURRENT_BINARY_DIR}/${_GEH_EXPORT_FILE_NAME}")