diff --git a/src/nghttpd.cc b/src/nghttpd.cc
index ef8eec61..518308b8 100644
--- a/src/nghttpd.cc
+++ b/src/nghttpd.cc
@@ -223,7 +223,6 @@ int main(int argc, char **argv) {
     int option_index = 0;
     int c = getopt_long(argc, argv, "DVb:c:d:ehm:n:p:va:w:W:", long_options,
                         &option_index);
-    char *end;
     if (c == -1) {
       break;
     }
@@ -256,11 +255,12 @@ int main(int argc, char **argv) {
       config.max_concurrent_streams = n;
       break;
     }
-    case 'n':
+    case 'n': {
 #ifdef NOTHREADS
       std::cerr << "-n: WARNING: Threading disabled at build time, "
                 << "no threads created." << std::endl;
 #else
+      char *end;
       errno = 0;
       config.num_worker = strtoul(optarg, &end, 10);
       if (errno == ERANGE || *end != '\0' || config.num_worker == 0) {
@@ -269,6 +269,7 @@ int main(int argc, char **argv) {
       }
 #endif // NOTHREADS
       break;
+    }
     case 'h':
       print_help(std::cout);
       exit(EXIT_SUCCESS);