diff --git a/include/migration/migration.h b/include/migration/migration.h
index 30c2913..2d5525c 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -39,8 +39,7 @@
 #define QEMU_VM_SECTION_FOOTER       0x7e
 
 struct MigrationParams {
-    bool blk;
-    bool shared;
+    bool unused; /* C doesn't allow empty structs */
 };
 
 /* Messages sent on the return path from destination to source */
diff --git a/migration/block.c b/migration/block.c
index 060087f..fcfa823 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -94,9 +94,6 @@ typedef struct BlkMigBlock {
 } BlkMigBlock;
 
 typedef struct BlkMigState {
-    /* Written during setup phase.  Can be read without a lock.  */
-    int blk_enable;
-    int shared_base;
     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
     int64_t total_sector_sum;
     bool zero_blocks;
@@ -425,7 +422,7 @@ static int init_blk_migration(QEMUFile *f)
         bmds->bulk_completed = 0;
         bmds->total_sectors = sectors;
         bmds->completed_sectors = 0;
-        bmds->shared_base = block_mig_state.shared_base;
+        bmds->shared_base = migrate_use_block_shared();
 
         assert(i < num_bs);
         bmds_bs[i].bmds = bmds;
@@ -994,22 +991,12 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
     return 0;
 }
 
-static void block_set_params(const MigrationParams *params, void *opaque)
-{
-    block_mig_state.blk_enable = params->blk;
-    block_mig_state.shared_base = params->shared;
-
-    /* shared base means that blk_enable = 1 */
-    block_mig_state.blk_enable |= params->shared;
-}
-
 static bool block_is_active(void *opaque)
 {
-    return block_mig_state.blk_enable == 1;
+    return migrate_use_block_enabled();
 }
 
 static SaveVMHandlers savevm_block_handlers = {
-    .set_params = block_set_params,
     .save_live_setup = block_save_setup,
     .save_live_iterate = block_save_iterate,
     .save_live_complete_precopy = block_save_complete,
diff --git a/migration/colo.c b/migration/colo.c
index 963c802..e772384 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -14,6 +14,7 @@
 #include "qemu/timer.h"
 #include "sysemu/sysemu.h"
 #include "migration/colo.h"
+#include "migration/block.h"
 #include "io/channel-buffer.h"
 #include "trace.h"
 #include "qemu/error-report.h"
@@ -345,8 +346,8 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
     }
 
     /* Disable block migration */
-    s->params.blk = 0;
-    s->params.shared = 0;
+    migrate_set_block_enabled(s, false);
+    migrate_set_block_shared(s, false);
     qemu_savevm_state_header(fb);
     qemu_savevm_state_begin(fb, &s->params);
     qemu_mutex_lock_iothread();
diff --git a/migration/migration.c b/migration/migration.c
index 2f981aa..8a3bf89 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -787,6 +787,10 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
         s->enabled_capabilities[cap->value->capability] = cap->value->state;
     }
 
+    if (s->enabled_capabilities[MIGRATION_CAPABILITY_BLOCK_SHARED]) {
+        s->enabled_capabilities[MIGRATION_CAPABILITY_BLOCK_ENABLED] = true;
+    }
+
     if (migrate_postcopy_ram()) {
         if (migrate_use_compression()) {
             /* The decompression threads asynchronously write into RAM
@@ -1214,9 +1218,6 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     MigrationParams params;
     const char *p;
 
-    params.blk = has_blk && blk;
-    params.shared = has_inc && inc;
-
     if (migration_is_setup_or_active(s->state) ||
         s->state == MIGRATION_STATUS_CANCELLING ||
         s->state == MIGRATION_STATUS_COLO) {
@@ -1239,6 +1240,7 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     }
 
     if (has_inc && inc) {
+        migrate_set_block_enabled(s, true);
         migrate_set_block_shared(s, true);
     }
 
diff --git a/migration/savevm.c b/migration/savevm.c
index f8d1e8b..221fb4b 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1233,8 +1233,6 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp)
 {
     int ret;
     MigrationParams params = {
-        .blk = 0,
-        .shared = 0
     };
     MigrationState *ms = migrate_init(&params);
     MigrationStatus status;
