diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 195924e7191..bc5d1c7443f 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -5107,6 +5107,8 @@ void Tokenizer::setVarIdPass2()
                 classnameTokens.push_back(tokStart->next());
                 tokStart = tokStart->tokAt(2);
             }
+            if (!tokStart)
+                syntaxError(tok);
         }
 
         std::string classname;
diff --git a/test/cli/fuzz-crash_c/crash-7af21bec1d9be105742fdcb336514aae26ab4425 b/test/cli/fuzz-crash_c/crash-7af21bec1d9be105742fdcb336514aae26ab4425
new file mode 100644
index 00000000000..6620c0d315f
--- /dev/null
+++ b/test/cli/fuzz-crash_c/crash-7af21bec1d9be105742fdcb336514aae26ab4425
@@ -0,0 +1,2 @@
+i
+class q::_
\ No newline at end of file