diff --git a/src/mgr/CMakeLists.txt b/src/mgr/CMakeLists.txt
index 55147af4fc6ba..8f39e41ac0694 100644
--- a/src/mgr/CMakeLists.txt
+++ b/src/mgr/CMakeLists.txt
@@ -33,6 +33,7 @@ if(WITH_MGR)
     mgr_commands.cc
     $<TARGET_OBJECTS:mgr_cap_obj>)
   add_executable(ceph-mgr ${mgr_srcs})
+  target_compile_definitions(ceph-mgr PRIVATE PY_SSIZE_T_CLEAN)
   if(WITH_LIBCEPHSQLITE)
     target_link_libraries(ceph-mgr cephsqlite SQLite3::SQLite3)
   endif()