diff --git a/osc/core.py b/osc/core.py
index 25c374a4b6..5250e3c230 100644
--- a/osc/core.py
+++ b/osc/core.py
@@ -8913,7 +8913,8 @@ def vc_export_env(apiurl: str, quiet=False):
 
     for (tag, val) in tag2val.items():
         for env in tag2envs[tag]:
-            os.environ[env] = val
+            if val:
+                os.environ[env] = val
 
 
 class MultibuildFlavorResolver: