diff --git a/src/compiler/lexer.c b/src/compiler/lexer.c
index bbedf6fc..0d6bedef 100644
--- a/src/compiler/lexer.c
+++ b/src/compiler/lexer.c
@@ -37,16 +37,24 @@ static void Lexer__dtor(Lexer* self) {
     c11_vector__dtor(&self->indents);
 }
 
+static const char* lexer_source_end(Lexer* self) {
+    return self->src->source->data + self->src->source->size;
+}
+
 static char eatchar(Lexer* self) {
+    const char* end = lexer_source_end(self);
+    if(self->curr_char > end) return '\0';
     char c = *self->curr_char;
     assert(c != '\n');  // eatchar() cannot consume a newline
-    self->curr_char++;
+    self->curr_char = (self->curr_char < end) ? self->curr_char + 1 : end + 1;
     return c;
 }
 
 static char eatchar_include_newline(Lexer* self) {
+    const char* end = lexer_source_end(self);
+    if(self->curr_char > end) return '\0';
     char c = *self->curr_char;
-    self->curr_char++;
+    self->curr_char = (self->curr_char < end) ? self->curr_char + 1 : end + 1;
     if(c == '\n') {
         self->current_line++;
         c11_vector__push(const char*, &self->src->line_starts, self->curr_char);
@@ -189,7 +197,8 @@ static Error* LexerError(Lexer* self, const char* fmt, ...) {
     err->src = self->src;
     PK_INCREF(self->src);
     err->lineno = self->current_line;
-    if(*self->curr_char == '\n') { err->lineno--; }
+    const char* end = lexer_source_end(self);
+    if(self->curr_char <= end && *self->curr_char == '\n') { err->lineno--; }
     va_list args;
     va_start(args, fmt);
     vsnprintf(err->msg, sizeof(err->msg), fmt, args);
diff --git a/src/public/PyList.c b/src/public/PyList.c
index a30c412d..88f2c843 100644
--- a/src/public/PyList.c
+++ b/src/public/PyList.c
@@ -384,7 +384,10 @@ static bool list_insert(int argc, py_Ref argv) {
     return true;
 }
 
-static int lt_with_key(py_TValue* a, py_TValue* b, py_TValue* key) {
+static int lt_with_key(const void* a_, const void* b_, void* extra) {
+    py_TValue* a = (py_TValue*)a_;
+    py_TValue* b = (py_TValue*)b_;
+    py_TValue* key = (py_TValue*)extra;
     if(!key) return py_less(a, b);
     VM* vm = pk_current_vm;
     // project a
@@ -416,7 +419,7 @@ static bool list_sort(int argc, py_Ref argv) {
     bool ok = c11__stable_sort(self->data,
                                self->length,
                                sizeof(py_TValue),
-                               (int (*)(const void*, const void*, void*))lt_with_key,
+                               lt_with_key,
                                key);
     if(!ok) return false;
 
diff --git a/tests/660_eval.py b/tests/660_eval.py
index 93c3e7a5..f0a88fc0 100644
--- a/tests/660_eval.py
+++ b/tests/660_eval.py
@@ -75,4 +75,11 @@ assert res == [42, 42]
 assert x == 33
 
 # test removing trailing newlines
-assert eval('[1, 2, 3]\n  \n') == [1, 2, 3]
\ No newline at end of file
+assert eval('[1, 2, 3]\n  \n') == [1, 2, 3]
+
+# lexer doesn't read past NUL on error at end of input
+try:
+    eval('"\\x4')
+    exit(1)
+except SyntaxError:
+    pass
\ No newline at end of file