diff --git a/sdk_container/src/third_party/portage-stable/dev-libs/gmp/gmp-6.3.0-r1.ebuild b/sdk_container/src/third_party/portage-stable/dev-libs/gmp/gmp-6.3.0-r1.ebuild
index 2cef81b66d..fae87d5caa 100644
--- a/sdk_container/src/third_party/portage-stable/dev-libs/gmp/gmp-6.3.0-r1.ebuild
+++ b/sdk_container/src/third_party/portage-stable/dev-libs/gmp/gmp-6.3.0-r1.ebuild
@@ -97,7 +97,7 @@ multilib_src_configure() {
 	# of platforms. Fix was maybe https://gmplib.org/repo/gmp-6.3/rev/9c324044f4b5.
 	filter-lto
 	# https://gmplib.org/list-archives/gmp-bugs/2024-November/005550.html
-	append-cflags -std=gnu17
+	append-cflags $(test-flags-CC -std=gnu17)
 
 	# Because of our 32-bit userland, 1.0 is the only HPPA ABI that works
 	# https://gmplib.org/manual/ABI-and-ISA.html#ABI-and-ISA (bug #344613)
@@ -117,7 +117,9 @@ multilib_src_configure() {
 
 	# https://gmplib.org/manual/Notes-for-Package-Builds
 	local myeconfargs=(
-		CC_FOR_BUILD="$(tc-getBUILD_CC)"
+		# -std=gnu99 appended here for bug #919935 to help
+		# prefix building w/ older compilers.
+		CC_FOR_BUILD="$(tc-getBUILD_CC) -std=gnu99"
 
 		--localstatedir="${EPREFIX}"/var/state/gmp
 		--enable-shared