diff --git a/sys-libs/glibc/glibc-2.38-r12.ebuild b/sys-libs/glibc/glibc-2.38-r12.ebuild
index aef3c5d5d4799..88280475bb10c 100644
--- a/sys-libs/glibc/glibc-2.38-r12.ebuild
+++ b/sys-libs/glibc/glibc-2.38-r12.ebuild
@@ -663,7 +663,7 @@ setup_env() {
 	# Some of the tests are written in C++, so we need to force our multlib abis in, bug 623548
 	export CXX="${glibc__GLIBC_CXX} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
-	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS}"
+	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
 	if is_crosscompile; then
 		# Assume worst-case bootstrap: glibc is built for the first time
diff --git a/sys-libs/glibc/glibc-2.39-r3.ebuild b/sys-libs/glibc/glibc-2.39-r3.ebuild
index f53dac7811b76..1e6aadbb04e31 100644
--- a/sys-libs/glibc/glibc-2.39-r3.ebuild
+++ b/sys-libs/glibc/glibc-2.39-r3.ebuild
@@ -676,7 +676,7 @@ setup_env() {
 	# Some of the tests are written in C++, so we need to force our multlib abis in, bug 623548
 	export CXX="${glibc__GLIBC_CXX} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
-	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS}"
+	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
 	if is_crosscompile; then
 		# Assume worst-case bootstrap: glibc is built for the first time
diff --git a/sys-libs/glibc/glibc-9999.ebuild b/sys-libs/glibc/glibc-9999.ebuild
index c6fc206e2d4fd..c3dce15e7e996 100644
--- a/sys-libs/glibc/glibc-9999.ebuild
+++ b/sys-libs/glibc/glibc-9999.ebuild
@@ -676,7 +676,7 @@ setup_env() {
 	# Some of the tests are written in C++, so we need to force our multlib abis in, bug 623548
 	export CXX="${glibc__GLIBC_CXX} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
-	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS}"
+	export CPP="${glibc__GLIBC_CPP} ${glibc__abi_CFLAGS} ${CFLAGS}"
 
 	if is_crosscompile; then
 		# Assume worst-case bootstrap: glibc is built for the first time