diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 92d7bbfc04..45ce29468f 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -4547,6 +4547,7 @@ void SubstitutionManager::init(DynamicPrintConfig* config, wxWindow* parent, wxF
     m_em = em_unit(parent);
 
     m_substitutions = m_config->option<ConfigOptionStrings>("gcode_substitutions")->values;
+    m_chb_match_single_lines.clear();
 }
 
 void SubstitutionManager::validate_length()