diff --git a/crates/ruff_python_parser/src/lexer.rs b/crates/ruff_python_parser/src/lexer.rs
index 24a4acb3ec..c3960d41cb 100644
--- a/crates/ruff_python_parser/src/lexer.rs
+++ b/crates/ruff_python_parser/src/lexer.rs
@@ -706,6 +706,8 @@ impl<'source> Lexer<'source> {
         // We reached end of file.
         // First of all, we need all nestings to be finished.
         if self.nesting > 0 {
+            // Reset the nesting to avoid going into infinite loop.
+            self.nesting = 0;
             return Err(LexicalError {
                 error: LexicalErrorType::Eof,
                 location: self.offset(),
@@ -1680,4 +1682,12 @@ def f(arg=%timeit a = b):
             ]
         );
     }
+
+    // This test case is to just make sure that the lexer doesn't go into
+    // infinite loop on invalid input.
+    #[test]
+    fn test_infite_loop() {
+        let source = "[1";
+        let _ = lex(source, Mode::Module).collect::<Vec<_>>();
+    }
 }