--- a/media-gfx/blender/blender-2.83.4-r1.ebuild	
+++ a/media-gfx/blender/blender-2.83.4-r1.ebuild	
@@ -114,6 +114,11 @@ BDEPEND="
 	nls? ( sys-devel/gettext )
 "
 
+PATCHES=(
+	# Fix compilation with sphinx-3 (ported from newer versions).
+	"${FILESDIR}/${P}-sphinx3.patch"
+)
+
 blender_check_requirements() {
 	[[ ${MERGE_TYPE} != binary ]] && use openmp && tc-check-openmp