diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index c5b619891d..fdac4d8981 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -1144,7 +1144,12 @@ std::string Print::validate() const
         // #4043
         if (total_copies_count > 1 && ! m_config.complete_objects.value)
             return L("The Spiral Vase option can only be used when printing a single object.");
-        if (m_regions.size() > 1)
+        assert(m_objects.size() == 1);
+        size_t num_regions = 0;
+        for (const std::vector<std::pair<t_layer_height_range, int>> &volumes_per_region : m_objects.front()->region_volumes)
+        	if (! volumes_per_region.empty())
+        		++ num_regions;
+        if (num_regions > 1)
             return L("The Spiral Vase option can only be used when printing single material objects.");
     }