diff --git a/src/std/link/lnkCalc.c b/src/std/link/lnkCalc.c
index b8cab4021..ea02ad039 100644
--- a/src/std/link/lnkCalc.c
+++ b/src/std/link/lnkCalc.c
@@ -287,6 +287,10 @@ static jlif_result lnkCalc_end_map(jlink *pjlink)
 
     if (clink->pstate == ps_error)
         return jlif_stop;
+    else if (!clink->post_expr) {
+        errlogPrintf("lnkCalc: no expression ('expr' key)\n");
+        return jlif_stop;
+    }
 
     return jlif_continue;
 }