diff --git a/tccpp.c b/tccpp.c
index ebbd051..6446c9c 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -1280,17 +1280,18 @@ static int macro_is_equal(const int *a, const int *b)
 {
     CValue cv;
     int t;
+    static CString localbuf;
 
     if (!a || !b)
         return 1;
 
     while (*a && *b) {
-        /* first time preallocate static cstr_buf, next time only reset position to start */
-        cstr_reset(&cstr_buf);
+        /* first time preallocate static localbuf, next time only reset position to start */
+        cstr_reset(&localbuf);
         TOK_GET(&t, &a, &cv);
-        cstr_cat(&cstr_buf, get_tok_str(t, &cv), 0);
+        cstr_cat(&localbuf, get_tok_str(t, &cv), 0);
         TOK_GET(&t, &b, &cv);
-        if (strcmp(cstr_buf.data, get_tok_str(t, &cv)))
+        if (strcmp(localbuf.data, get_tok_str(t, &cv)))
             return 0;
     }
     return !(*a || *b);
diff --git a/tests/pp/16.c b/tests/pp/16.c
new file mode 100644
index 0000000..8b5b642
--- /dev/null
+++ b/tests/pp/16.c
@@ -0,0 +1,3 @@
+/* The following should warn */
+#define A ...
+#define A <<=
diff --git a/tests/pp/16.expect b/tests/pp/16.expect
new file mode 100644
index 0000000..695d6d4
--- /dev/null
+++ b/tests/pp/16.expect
@@ -0,0 +1,2 @@
+
+16.c:3: warning: A redefined