--- ilmbase-2.1.0.ebuild
+++ ilmbase-2.1.0.ebuild
@@ -16,3 +16,11 @@
 
 DOCS=( AUTHORS ChangeLog NEWS README )
 MULTILIB_WRAPPED_HEADERS=( /usr/include/OpenEXR/IlmBaseConfig.h )
+
+src_configure() {
+	# Disable use of ucontext.h for PPC wrt #482890
+	if use ppc || use ppc64; then
+		export ac_cv_header_ucontext_h=no
+	fi
+	autotools-multilib_src_configure
+}