diff --git a/parse.c b/parse.c
index 08a482e..bff47ef 100644
--- a/parse.c
+++ b/parse.c
@@ -3163,15 +3163,29 @@ static Token *function(Token *tok, Type *basety, VarAttr *attr) {
   Type *ty = declarator(&tok, tok, basety);
   if (!ty->name)
     error_tok(ty->name_pos, "function name omitted");
+  char *name_str = get_ident(ty->name);
+
+  Obj *fn = find_func(name_str);
+  if (fn) {
+    // Redeclaration
+    if (!fn->is_function)
+      error_tok(tok, "redeclared as a different kind of symbol");
+    if (fn->is_definition && equal(tok, "{"))
+      error_tok(tok, "redefinition of %s", name_str);
+    if (!fn->is_static && attr->is_static)
+      error_tok(tok, "static declaration follows a non-static declaration");
+    fn->is_definition = fn->is_definition || equal(tok, "{");
+  } else {
+    fn = new_gvar(name_str, ty);
+    fn->is_function = true;
+    fn->is_definition = equal(tok, "{");
+    fn->is_static = attr->is_static || (attr->is_inline && !attr->is_extern);
+    fn->is_inline = attr->is_inline;
+  }
 
-  Obj *fn = new_gvar(get_ident(ty->name), ty);
-  fn->is_function = true;
-  fn->is_definition = !consume(&tok, tok, ";");
-  fn->is_static = attr->is_static || (attr->is_inline && !attr->is_extern);
-  fn->is_inline = attr->is_inline;
   fn->is_root = !(fn->is_static && fn->is_inline);
 
-  if (!fn->is_definition)
+  if (consume(&tok, tok, ";"))
     return tok;
 
   current_fn = fn;