diff --git a/src/shared/varlink-io.systemd.Unit.c b/src/shared/varlink-io.systemd.Unit.c
index 3fa64859ef..1cdb52de14 100644
--- a/src/shared/varlink-io.systemd.Unit.c
+++ b/src/shared/varlink-io.systemd.Unit.c
@@ -533,7 +533,7 @@ static SD_VARLINK_DEFINE_STRUCT_TYPE(
                 SD_VARLINK_FIELD_COMMENT("https://www.freedesktop.org/software/systemd/man"PROJECT_VERSION_STR"systemd.exec.html#MemoryKSM="),
                 SD_VARLINK_DEFINE_FIELD(MemoryKSM, SD_VARLINK_BOOL, SD_VARLINK_NULLABLE),
                 SD_VARLINK_FIELD_COMMENT("https://www.freedesktop.org/software/systemd/man"PROJECT_VERSION_STR"systemd.exec.html#MemoryTHP="),
-                SD_VARLINK_DEFINE_FIELD(MemoryTHP, SD_VARLINK_STRING, SD_VARLINK_NULLABLE),
+                SD_VARLINK_DEFINE_FIELD(MemoryTHP, SD_VARLINK_STRING, 0),
 
                 /* Sandboxing
                  * https://www.freedesktop.org/software/systemd/man/latest/systemd.exec.html#Sandboxing */