diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-0.17.ebuild b/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-0.17.ebuild
index 4f44e489c9..6fb6f4f13f 100644
--- a/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-0.17.ebuild
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-0.17.ebuild
@@ -1,4 +1,4 @@
-# Copyright 1999-2023 Gentoo Authors
+# Copyright 1999-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
@@ -19,6 +19,9 @@ MULTILIB_WRAPPED_HEADERS=(
 )
 
 multilib_src_configure() {
+	# Tests use Valgrind automagically otherwise (bug #927027)
+	export USE_VALGRIND=0
+
 	local mycmakeargs=(
 		# apps are not installed, so disable unconditionally.
 		# https://github.com/json-c/json-c/blob/json-c-0.17-20230812/apps/CMakeLists.txt#L119...L121
diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-9999.ebuild b/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-9999.ebuild
index 29dc876b22..2ee46fcafd 100644
--- a/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-9999.ebuild
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/json-c/json-c-9999.ebuild
@@ -20,6 +20,9 @@ MULTILIB_WRAPPED_HEADERS=(
 )
 
 multilib_src_configure() {
+	# Tests use Valgrind automagically otherwise (bug #927027)
+	export USE_VALGRIND=0
+
 	local mycmakeargs=(
 		# apps are not installed, so disable unconditionally.
 		# https://github.com/json-c/json-c/blob/json-c-0.17-20230812/apps/CMakeLists.txt#L119...L121