diff --git a/sci-misc/stable-diffusion-cpp/stable-diffusion-cpp-9999.ebuild b/sci-misc/stable-diffusion-cpp/stable-diffusion-cpp-9999.ebuild
index 803d7f0977..71a225d1ef 100644
--- a/sci-misc/stable-diffusion-cpp/stable-diffusion-cpp-9999.ebuild
+++ b/sci-misc/stable-diffusion-cpp/stable-diffusion-cpp-9999.ebuild
@@ -89,6 +89,7 @@ src_configure() {
 		-DSD_CUDA=$(usex cuda)
 		-DSD_OPENCL=$(usex opencl)
 		-DSD_WEBP=$(usex webp)
+		-DSD_USE_SYSTEM_WEBP=$(usex webp)
 		-DSD_VULKAN=$(usex vulkan)
 
 		# avoid clashing with whisper.cpp