diff --git a/sci-physics/lhapdf/lhapdf-6.3.0-r2.ebuild b/sci-physics/lhapdf/lhapdf-6.3.0-r2.ebuild
index 01884ec1f0fef..acccf2facc60e 100644
--- a/sci-physics/lhapdf/lhapdf-6.3.0-r2.ebuild
+++ b/sci-physics/lhapdf/lhapdf-6.3.0-r2.ebuild
@@ -52,7 +52,7 @@ src_prepare() {
 }
 
 src_configure() {
-	CONFIG_SHELL="${EPREFIX}/bin/bash" \
+	local -x CONFIG_SHELL="${EPREFIX}/bin/bash"
 	econf \
 		--disable-static \
 		--enable-python
diff --git a/sci-physics/lhapdf/lhapdf-6.5.3-r1.ebuild b/sci-physics/lhapdf/lhapdf-6.5.3-r1.ebuild
index fff2f8d0b310e..fc31840790970 100644
--- a/sci-physics/lhapdf/lhapdf-6.5.3-r1.ebuild
+++ b/sci-physics/lhapdf/lhapdf-6.5.3-r1.ebuild
@@ -36,7 +36,7 @@ PATCHES=(
 )
 
 src_configure() {
-	CONFIG_SHELL="${EPREFIX}/bin/bash" \
+	local -x CONFIG_SHELL="${EPREFIX}/bin/bash"
 	econf \
 		--disable-static \
 		--enable-python
diff --git a/sci-physics/lhapdf/lhapdf-6.5.4-r1.ebuild b/sci-physics/lhapdf/lhapdf-6.5.4-r1.ebuild
index 7a306b01aeeb5..7e3801a3d0e31 100644
--- a/sci-physics/lhapdf/lhapdf-6.5.4-r1.ebuild
+++ b/sci-physics/lhapdf/lhapdf-6.5.4-r1.ebuild
@@ -54,7 +54,7 @@ src_prepare() {
 }
 
 src_configure() {
-	CONFIG_SHELL="${EPREFIX}/bin/bash" \
+	local -x CONFIG_SHELL="${EPREFIX}/bin/bash"
 	econf \
 		--disable-static \
 		$(use_enable python)