diff --git a/externals/CMakeLists.txt b/externals/CMakeLists.txt
index fc45473b6..788992d81 100644
--- a/externals/CMakeLists.txt
+++ b/externals/CMakeLists.txt
@@ -392,6 +392,7 @@ if (ENABLE_VULKAN)
         set(ENABLE_CTEST OFF CACHE BOOL "")
         set(ENABLE_HLSL OFF CACHE BOOL "")
         set(BUILD_EXTERNAL OFF CACHE BOOL "")
+        set(ALLOW_EXTERNAL_SPIRV_TOOLS ON)
         add_subdirectory(glslang)
     endif()