diff --git a/src/include/atomic.h b/src/include/atomic.h
index 55f7290ac87..88c9bfd3871 100644
--- a/src/include/atomic.h
+++ b/src/include/atomic.h
@@ -122,7 +122,7 @@ namespace ceph {
 #if SIZEOF_AO_T == 8
   typedef atomic_t atomic64_t;
 #else
-  typedef atomic_spinlock_t<long long> atomic64_t;
+  typedef atomic_spinlock_t<unsigned long long> atomic64_t;
 #endif
 
 }
diff --git a/src/librados/librados.cc b/src/librados/librados.cc
index 2358fb406e8..26b94bd591b 100644
--- a/src/librados/librados.cc
+++ b/src/librados/librados.cc
@@ -2058,10 +2058,10 @@ extern "C" int rados_pool_list(rados_t cluster, char *buf, size_t len)
   std::list<std::string>::const_iterator i = pools.begin();
   std::list<std::string>::const_iterator p_end = pools.end();
   for (; i != p_end; ++i) {
-    if (len == 0)
-      break;
     int rl = i->length() + 1;
-    strncat(b, i->c_str(), len - 2); // leave space for two NULLs
+    if (len < (unsigned)rl)
+      break;
+    strncat(b, i->c_str(), rl);
     needed += rl;
     len -= rl;
     b += rl;
diff --git a/src/test/librados/pool.cc b/src/test/librados/pool.cc
index 65d5c226331..04286fcf32a 100644
--- a/src/test/librados/pool.cc
+++ b/src/test/librados/pool.cc
@@ -8,8 +8,8 @@
 #define POOL_LIST_BUF_SZ 32768
 
 TEST(LibRadosPools, PoolList) {
-  std::vector<char> pool_list_buf(POOL_LIST_BUF_SZ, '\0');
-  char *buf = &pool_list_buf[0];
+  char pool_list_buf[POOL_LIST_BUF_SZ];
+  char *buf = pool_list_buf;
   rados_t cluster;
   std::string pool_name = get_temp_pool_name();
   ASSERT_EQ("", create_one_pool(pool_name, &cluster));
@@ -23,6 +23,14 @@ TEST(LibRadosPools, PoolList) {
     buf += strlen(buf) + 1;
   }
   ASSERT_EQ(found_pool, true);
+
+  // make sure we honor the buffer size limit
+  buf = pool_list_buf;
+  memset(buf, 0, POOL_LIST_BUF_SZ);
+  ASSERT_LT(rados_pool_list(cluster, buf, 20), POOL_LIST_BUF_SZ);
+  ASSERT_NE(0, buf[0]);  // include at least one pool name
+  ASSERT_EQ(0, buf[20]);  // but don't touch the stopping point
+
   ASSERT_EQ(0, destroy_one_pool(pool_name, &cluster));
 }