diff --git a/lib/checkunusedfunctions.cpp b/lib/checkunusedfunctions.cpp
index e2eb8452b..738136ccc 100644
--- a/lib/checkunusedfunctions.cpp
+++ b/lib/checkunusedfunctions.cpp
@@ -95,10 +95,13 @@ void CheckUnusedFunctions::parseTokens(const Tokenizer &tokenizer, const char Fi
         // parsing of library code to find called functions
         if (settings->library.isexecutableblock(FileName, tok->str())) {
             const Token * markupVarToken = tok->tokAt(settings->library.blockstartoffset(FileName));
+            // not found
+            if (!markupVarToken)
+                continue;
             int scope = 0;
             bool start = true;
             // find all function calls in library code (starts with '(', not if or while etc)
-            while (scope || start) {
+            while ((scope || start) && markupVarToken) {
                 if (markupVarToken->str() == settings->library.blockstart(FileName)) {
                     scope++;
                     if (start) {