diff --git a/persistent-data/space-maps/disk.cc b/persistent-data/space-maps/disk.cc
index 9e435b6..36937ec 100644
--- a/persistent-data/space-maps/disk.cc
+++ b/persistent-data/space-maps/disk.cc
@@ -21,6 +21,7 @@
 #include "persistent-data/space-maps/recursive.h"
 #include "persistent-data/space-maps/careful_alloc.h"
 
+#include "persistent-data/data-structures/btree_checker.h"
 #include "persistent-data/checksum.h"
 #include "persistent-data/endian_utils.h"
 #include "persistent-data/math_utils.h"
diff --git a/persistent-data/space-maps/disk.h b/persistent-data/space-maps/disk.h
index 070bc44..5241419 100644
--- a/persistent-data/space-maps/disk.h
+++ b/persistent-data/space-maps/disk.h
@@ -19,8 +19,7 @@
 #ifndef SPACE_MAP_DISK_H
 #define SPACE_MAP_DISK_H
 
-// FIXME: why is btree_checker needed?
-#include "persistent-data/data-structures/btree_checker.h"
+#include "persistent-data/transaction_manager.h"
 #include "persistent-data/space_map.h"
 
 //----------------------------------------------------------------
diff --git a/unit-tests/endian_t.cc b/unit-tests/endian_t.cc
index b055318..9fbbc06 100644
--- a/unit-tests/endian_t.cc
+++ b/unit-tests/endian_t.cc
@@ -17,10 +17,9 @@
 // <http://www.gnu.org/licenses/>.
 
 #include "gmock/gmock.h"
-#include "persistent-data/space-maps/disk.h"
+#include "persistent-data/endian_utils.h"
 
 using namespace base;
-using namespace persistent_data;
 using namespace std;
 using namespace testing;