diff --git a/src/scanner.cc b/src/scanner.cc
index 6636338..15de616 100644
--- a/src/scanner.cc
+++ b/src/scanner.cc
@@ -27,7 +27,7 @@ struct Scanner {
 
   unsigned serialize(char *buffer) {
     unsigned i = 0;
-    size_t n = tags.size();
+    unsigned n = tags.size();
     std::memcpy(buffer, &n, sizeof(n));
     i += sizeof(n);
     for (unsigned j = 0; j < n; j++) {
@@ -51,7 +51,7 @@ struct Scanner {
     tags.clear();
     if (length > 0) {
       unsigned i = 0;
-      size_t n;
+      unsigned n;
       std::memcpy(&n, buffer, sizeof(n));
       i += sizeof(n);
       tags.resize(n);