diff --git a/src/test/librados/io.cc b/src/test/librados/io.cc
index 0dadf9585c5..5daca3c15ec 100644
--- a/src/test/librados/io.cc
+++ b/src/test/librados/io.cc
@@ -621,9 +621,9 @@ TEST_F(LibRadosIoEC, OverlappingWriteRoundTrip) {
   char *buf3 = (char *)new char[dbsize];
   memset(buf, 0xcc, dbsize);
   ASSERT_EQ(0, rados_write(ioctx, "foo", buf, dbsize, 0));
-  memset(buf2, 0xdd, sizeof(buf2));
+  memset(buf2, 0xdd, bsize);
   ASSERT_EQ(-EOPNOTSUPP, rados_write(ioctx, "foo", buf2, bsize, 0));
-  memset(buf3, 0xdd, sizeof(buf3));
+  memset(buf3, 0xdd, dbsize);
   ASSERT_EQ(dbsize, rados_read(ioctx, "foo", buf3, dbsize, 0));
   // Read the same as first write
   ASSERT_EQ(0, memcmp(buf3, buf, dbsize));
diff --git a/src/test/librados/misc.cc b/src/test/librados/misc.cc
index f0f8447748f..ea990b50a98 100644
--- a/src/test/librados/misc.cc
+++ b/src/test/librados/misc.cc
@@ -451,7 +451,7 @@ TEST_F(LibRadosMiscPP, CloneRangePP) {
   memset(buf, 0xcc, sizeof(buf));
   bufferlist bl;
   bl.append(buf, sizeof(buf));
-  ASSERT_EQ(0, (size_t)ioctx.write("foo", bl, sizeof(buf), 0));
+  ASSERT_EQ(0, ioctx.write("foo", bl, sizeof(buf), 0));
   ioctx.locator_set_key("foo");
   ASSERT_EQ(0, ioctx.clone_range("bar", 0, "foo", 0, sizeof(buf)));
   bufferlist bl2;
diff --git a/src/test/librados/snapshots.cc b/src/test/librados/snapshots.cc
index e490a088379..832dcab1c80 100644
--- a/src/test/librados/snapshots.cc
+++ b/src/test/librados/snapshots.cc
@@ -610,7 +610,7 @@ TEST_F(LibRadosSnapshotsSelfManagedEC, Snap) {
 					&my_snaps[0], my_snaps.size()));
   ::std::reverse(my_snaps.begin(), my_snaps.end());
   char *buf2 = (char *)new char[bsize];
-  memset(buf2, 0xdd, sizeof(buf2));
+  memset(buf2, 0xdd, bsize);
   ASSERT_EQ(0, rados_write(ioctx, "foo", buf2, bsize, bsize));
   rados_ioctx_snap_set_read(ioctx, my_snaps[1]-1);
   char *buf3 = (char *)new char[bsize*2];
@@ -641,7 +641,7 @@ TEST_F(LibRadosSnapshotsSelfManagedEC, Rollback) {
   ::std::reverse(my_snaps.begin(), my_snaps.end());
   int bsize = alignment;
   char *buf = (char *)new char[bsize];
-  memset(buf, 0xcc, sizeof(buf));
+  memset(buf, 0xcc, bsize);
   ASSERT_EQ(0, rados_write(ioctx, "foo", buf, bsize, 0));
 
   my_snaps.push_back(-2);
@@ -651,7 +651,7 @@ TEST_F(LibRadosSnapshotsSelfManagedEC, Rollback) {
 					&my_snaps[0], my_snaps.size()));
   ::std::reverse(my_snaps.begin(), my_snaps.end());
   char *buf2 = (char *)new char[bsize];
-  memset(buf2, 0xdd, sizeof(buf2));
+  memset(buf2, 0xdd, bsize);
 
   ASSERT_EQ(0, rados_write(ioctx, "foo", buf2, bsize, bsize));
   rados_ioctx_selfmanaged_snap_rollback(ioctx, "foo", my_snaps[1]);
@@ -678,7 +678,7 @@ TEST_F(LibRadosSnapshotsSelfManagedECPP, SnapPP) {
   ::std::reverse(my_snaps.begin(), my_snaps.end());
   int bsize = alignment;
   char *buf = (char *)new char[bsize];
-  memset(buf, 0xcc, sizeof(buf));
+  memset(buf, 0xcc, bsize);
   bufferlist bl1;
   bl1.append(buf, bsize);
   ASSERT_EQ(0, ioctx.write("foo", bl1, bsize, 0));