diff --git a/tests/overlay-local-store/build-inner.sh b/tests/overlay-local-store/build-inner.sh
index 969de282d..beb40b2fc 100755
--- a/tests/overlay-local-store/build-inner.sh
+++ b/tests/overlay-local-store/build-inner.sh
@@ -6,6 +6,10 @@ set -x
 
 source common.sh
 
+# Avoid store dir being inside sandbox build-dir
+unset NIX_STORE_DIR
+unset NIX_STATE_DIR
+
 storeDirs
 
 initLowerStore
diff --git a/tests/overlay-local-store/check-post-init-inner.sh b/tests/overlay-local-store/check-post-init-inner.sh
index 421b64934..37ed8c113 100755
--- a/tests/overlay-local-store/check-post-init-inner.sh
+++ b/tests/overlay-local-store/check-post-init-inner.sh
@@ -6,6 +6,10 @@ set -x
 
 source common.sh
 
+# Avoid store dir being inside sandbox build-dir
+unset NIX_STORE_DIR
+unset NIX_STATE_DIR
+
 storeDirs
 
 initLowerStore
diff --git a/tests/overlay-local-store/redundant-add-inner.sh b/tests/overlay-local-store/redundant-add-inner.sh
index 921069c25..97969b40e 100755
--- a/tests/overlay-local-store/redundant-add-inner.sh
+++ b/tests/overlay-local-store/redundant-add-inner.sh
@@ -6,6 +6,10 @@ set -x
 
 source common.sh
 
+# Avoid store dir being inside sandbox build-dir
+unset NIX_STORE_DIR
+unset NIX_STATE_DIR
+
 storeDirs
 
 initLowerStore