diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index b29e807b8b5..61719f5291d 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -3470,6 +3470,8 @@ bool Tokenizer::simplifyUsing()
                 skip = true;
                 simplifyUsingError(usingStart, usingEnd);
             }
+            if (!after)
+                syntaxError(tok1);
             tok1 = after->previous();
         }
 
diff --git a/test/cli/fuzz-crash/crash-42dad53b40278386e4ebd224813e26541cc725f1 b/test/cli/fuzz-crash/crash-42dad53b40278386e4ebd224813e26541cc725f1
new file mode 100644
index 00000000000..3a9abbf229f
--- /dev/null
+++ b/test/cli/fuzz-crash/crash-42dad53b40278386e4ebd224813e26541cc725f1
@@ -0,0 +1 @@
+using C=C*;C{{}}