diff --git a/lib/stack b/lib/stack
index 6ca6c0baf2..9a509d8318 100644
--- a/lib/stack
+++ b/lib/stack
@@ -18,7 +18,7 @@ function stack_install_service {
     if type install_${service} >/dev/null 2>&1; then
         if [[ -n ${PROJECT_VENV[$service]:-} ]]; then
             rm -rf ${PROJECT_VENV[$service]}
-            source tools/build_venv.sh ${PROJECT_VENV[$service]}
+            source $TOP_DIR/tools/build_venv.sh ${PROJECT_VENV[$service]}
             export PIP_VIRTUAL_ENV=${PROJECT_VENV[$service]:-}
         fi
         install_${service}
diff --git a/stack.sh b/stack.sh
index 0ec7a5e5e5..6002cf9d17 100755
--- a/stack.sh
+++ b/stack.sh
@@ -685,7 +685,7 @@ fi
 
 # Pre-build some problematic wheels
 if [[ ! -d ${WHEELHOUSE:-} ]]; then
-    source tools/build_wheels.sh
+    source $TOP_DIR/tools/build_wheels.sh
 fi