diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index 594de5c0295..847af978292 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -2029,9 +2029,9 @@ void TokenList::validateAst(bool print) const
                                     "' doesn't have two operands.",
                                     InternalError::AST);
         }
-        if (tok->str() == "case" && !tok->astOperand1()) {
+        if (!tok->astOperand1() && Token::Match(tok, "case|!")) {
             throw InternalError(tok,
-                                "Syntax Error: AST broken, 'case' doesn't have an operand.",
+                                "Syntax Error: AST broken, '" + tok->str() + "' doesn't have an operand.",
                                 InternalError::AST);
         }
 
diff --git a/test/cli/fuzz-crash_c/crash-401f925d3c6fd78f864ffd7bf0531bd6a76bb832 b/test/cli/fuzz-crash_c/crash-401f925d3c6fd78f864ffd7bf0531bd6a76bb832
new file mode 100644
index 00000000000..a778e6e2823
--- /dev/null
+++ b/test/cli/fuzz-crash_c/crash-401f925d3c6fd78f864ffd7bf0531bd6a76bb832
@@ -0,0 +1 @@
+i(){!!:!=!&&d}