diff --git a/include/jemalloc/internal/arena_inlines_b.h b/include/jemalloc/internal/arena_inlines_b.h
index eac4a631..fd641754 100644
--- a/include/jemalloc/internal/arena_inlines_b.h
+++ b/include/jemalloc/internal/arena_inlines_b.h
@@ -148,15 +148,18 @@ arena_decay_extent(tsdn_t *tsdn,arena_t *arena, ehooks_t *ehooks,
 	extent_dalloc_wrapper(tsdn, arena, ehooks, edata);
 	if (config_stats) {
 		/* Update stats accordingly. */
-		LOCKEDINT_MTX_LOCK(tsdn, arena->stats.mtx);
-		locked_inc_u64(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
+		LOCKEDINT_MTX_LOCK(tsdn, *arena->pa_shard.stats_mtx);
+		locked_inc_u64(tsdn,
+		    LOCKEDINT_MTX(*arena->pa_shard.stats_mtx),
 		    &arena->pa_shard.stats->decay_dirty.nmadvise, 1);
-		locked_inc_u64(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
+		locked_inc_u64(tsdn,
+		    LOCKEDINT_MTX(*arena->pa_shard.stats_mtx),
 		    &arena->pa_shard.stats->decay_dirty.purged,
 		    extent_size >> LG_PAGE);
-		locked_dec_zu(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
-		    &arena->stats.mapped, extent_size);
-		LOCKEDINT_MTX_UNLOCK(tsdn, arena->stats.mtx);
+		locked_dec_zu(tsdn,
+		    LOCKEDINT_MTX(*arena->pa_shard.stats_mtx),
+		    &arena->pa_shard.stats->mapped, extent_size);
+		LOCKEDINT_MTX_UNLOCK(tsdn, *arena->pa_shard.stats_mtx);
 	}
 }
 
diff --git a/include/jemalloc/internal/arena_stats.h b/include/jemalloc/internal/arena_stats.h
index 82996b8b..129a8fef 100644
--- a/include/jemalloc/internal/arena_stats.h
+++ b/include/jemalloc/internal/arena_stats.h
@@ -61,12 +61,6 @@ struct arena_stats_extents_s {
 typedef struct arena_stats_s arena_stats_t;
 struct arena_stats_s {
 	LOCKEDINT_MTX_DECLARE(mtx)
-
-	/*
-	 * Number of bytes currently mapped, excluding retained memory.
-	 */
-	locked_zu_t		mapped; /* Partially derived. */
-
 	/*
 	 * Number of unused virtual memory bytes currently retained.  Retained
 	 * bytes are technically mapped (though always decommitted or purged),
@@ -135,12 +129,4 @@ arena_stats_large_flush_nrequests_add(tsdn_t *tsdn, arena_stats_t *arena_stats,
 	LOCKEDINT_MTX_UNLOCK(tsdn, arena_stats->mtx);
 }
 
-static inline void
-arena_stats_mapped_add(tsdn_t *tsdn, arena_stats_t *arena_stats, size_t size) {
-	LOCKEDINT_MTX_LOCK(tsdn, arena_stats->mtx);
-	locked_inc_zu(tsdn, LOCKEDINT_MTX(arena_stats->mtx),
-	    &arena_stats->mapped, size);
-	LOCKEDINT_MTX_UNLOCK(tsdn, arena_stats->mtx);
-}
-
 #endif /* JEMALLOC_INTERNAL_ARENA_STATS_H */
diff --git a/include/jemalloc/internal/pa.h b/include/jemalloc/internal/pa.h
index a7c57896..61b6f42c 100644
--- a/include/jemalloc/internal/pa.h
+++ b/include/jemalloc/internal/pa.h
@@ -35,6 +35,14 @@ typedef struct pa_shard_stats_s pa_shard_stats_t;
 struct pa_shard_stats_s {
 	pa_shard_decay_stats_t decay_dirty;
 	pa_shard_decay_stats_t decay_muzzy;
+	/*
+	 * Number of bytes currently mapped, excluding retained memory.
+	 *
+	 * Partially derived -- we maintain our own counter, but add in the
+	 * base's own counter at merge.
+	 */
+	locked_zu_t mapped;
+
 	/* VM space had to be leaked (undocumented).  Normally 0. */
 	atomic_zu_t abandoned_vm;
 };
@@ -60,12 +68,21 @@ struct pa_shard_s {
 	/* Extent serial number generator state. */
 	atomic_zu_t extent_sn_next;
 
+	malloc_mutex_t *stats_mtx;
 	pa_shard_stats_t *stats;
 };
 
+static inline void
+pa_shard_stats_mapped_add(tsdn_t *tsdn, pa_shard_t *shard, size_t size) {
+	LOCKEDINT_MTX_LOCK(tsdn, *shard->stats_mtx);
+	locked_inc_zu(tsdn, LOCKEDINT_MTX(*shard->stats_mtx),
+	    &shard->stats->mapped, size);
+	LOCKEDINT_MTX_UNLOCK(tsdn, *shard->stats_mtx);
+}
+
 /* Returns true on error. */
 bool pa_shard_init(tsdn_t *tsdn, pa_shard_t *shard, base_t *base, unsigned ind,
-    pa_shard_stats_t *stats);
+    pa_shard_stats_t *stats, malloc_mutex_t *stats_mtx);
 size_t pa_shard_extent_sn_next(pa_shard_t *shard);
 
 #endif /* JEMALLOC_INTERNAL_PA_H */
diff --git a/src/arena.c b/src/arena.c
index 8f306604..2f626fed 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -95,9 +95,10 @@ arena_stats_merge(tsdn_t *tsdn, arena_t *arena, unsigned *nthreads,
 
 	LOCKEDINT_MTX_LOCK(tsdn, arena->stats.mtx);
 
-	locked_inc_zu_unsynchronized(&astats->mapped, base_mapped
-	    + locked_read_zu(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
-	    &arena->stats.mapped));
+	locked_inc_zu_unsynchronized(&astats->pa_shard_stats.mapped,
+	    base_mapped + locked_read_zu(tsdn,
+	    LOCKEDINT_MTX(*arena->pa_shard.stats_mtx),
+	    &arena->pa_shard.stats->mapped));
 	locked_inc_zu_unsynchronized(&astats->retained,
 	    ecache_npages_get(&arena->pa_shard.ecache_retained) << LG_PAGE);
 
@@ -488,7 +489,7 @@ arena_extent_alloc_large(tsdn_t *tsdn, arena_t *arena, size_t usize,
 			if (mapped_add != 0) {
 				locked_inc_zu(tsdn,
 				    LOCKEDINT_MTX(arena->stats.mtx),
-				    &arena->stats.mapped, mapped_add);
+				    &arena->pa_shard.stats->mapped, mapped_add);
 			}
 			LOCKEDINT_MTX_UNLOCK(tsdn, arena->stats.mtx);
 		}
@@ -919,7 +920,7 @@ arena_decay_stashed(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks,
 		locked_inc_u64(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
 		&decay->stats->purged, npurged);
 		locked_dec_zu(tsdn, LOCKEDINT_MTX(arena->stats.mtx),
-		    &arena->stats.mapped, nunmapped << LG_PAGE);
+		    &arena->pa_shard.stats->mapped, nunmapped << LG_PAGE);
 		LOCKEDINT_MTX_UNLOCK(tsdn, arena->stats.mtx);
 	}
 
@@ -1240,7 +1241,7 @@ arena_slab_alloc_hard(tsdn_t *tsdn, arena_t *arena, ehooks_t *ehooks,
 	    true, szind, &zero);
 
 	if (config_stats && slab != NULL) {
-		arena_stats_mapped_add(tsdn, &arena->stats,
+		pa_shard_stats_mapped_add(tsdn, &arena->pa_shard,
 		    bin_info->slab_size);
 	}
 
@@ -2039,7 +2040,7 @@ arena_new(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks) {
 	}
 
 	if (pa_shard_init(tsdn, &arena->pa_shard, base, ind,
-	    &arena->stats.pa_shard_stats)) {
+	    &arena->stats.pa_shard_stats, LOCKEDINT_MTX(arena->stats.mtx))) {
 		goto label_error;
 	}
 
diff --git a/src/ctl.c b/src/ctl.c
index 26d86da0..122856c0 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -861,8 +861,9 @@ ctl_arena_stats_sdmerge(ctl_arena_t *ctl_sdarena, ctl_arena_t *ctl_arena,
 		ctl_arena_stats_t *astats = ctl_arena->astats;
 
 		if (!destroyed) {
-			ctl_accum_locked_zu(&sdstats->astats.mapped,
-			    &astats->astats.mapped);
+			ctl_accum_locked_zu(
+			    &sdstats->astats.pa_shard_stats.mapped,
+			    &astats->astats.pa_shard_stats.mapped);
 			ctl_accum_locked_zu(&sdstats->astats.retained,
 			    &astats->astats.retained);
 			ctl_accum_atomic_zu(&sdstats->astats.edata_avail,
@@ -1103,7 +1104,7 @@ ctl_refresh(tsdn_t *tsdn) {
 		ctl_stats->resident = atomic_load_zu(
 		    &ctl_sarena->astats->astats.resident, ATOMIC_RELAXED);
 		ctl_stats->mapped = locked_read_atomic_zu(
-		    &ctl_sarena->astats->astats.mapped);
+		    &ctl_sarena->astats->astats.pa_shard_stats.mapped);
 		ctl_stats->retained = locked_read_atomic_zu(
 		    &ctl_sarena->astats->astats.retained);
 
@@ -2914,8 +2915,8 @@ CTL_RO_GEN(stats_arenas_i_pactive, arenas_i(mib[2])->pactive, size_t)
 CTL_RO_GEN(stats_arenas_i_pdirty, arenas_i(mib[2])->pdirty, size_t)
 CTL_RO_GEN(stats_arenas_i_pmuzzy, arenas_i(mib[2])->pmuzzy, size_t)
 CTL_RO_CGEN(config_stats, stats_arenas_i_mapped,
-    locked_read_atomic_zu(&arenas_i(mib[2])->astats->astats.mapped),
-    size_t)
+    locked_read_atomic_zu(&arenas_i(
+    mib[2])->astats->astats.pa_shard_stats.mapped), size_t)
 CTL_RO_CGEN(config_stats, stats_arenas_i_retained,
     locked_read_atomic_zu(&arenas_i(mib[2])->astats->astats.retained),
     size_t)
diff --git a/src/large.c b/src/large.c
index fa03a50e..57bf6748 100644
--- a/src/large.c
+++ b/src/large.c
@@ -151,7 +151,7 @@ large_ralloc_no_move_expand(tsdn_t *tsdn, edata_t *edata, size_t usize,
 	emap_remap(tsdn, &emap_global, edata, szind, false);
 
 	if (config_stats && new_mapping) {
-		arena_stats_mapped_add(tsdn, &arena->stats, trailsize);
+		pa_shard_stats_mapped_add(tsdn, &arena->pa_shard, trailsize);
 	}
 
 	if (zero) {
diff --git a/src/pa.c b/src/pa.c
index 35d3335f..e4dbb040 100644
--- a/src/pa.c
+++ b/src/pa.c
@@ -3,7 +3,7 @@
 
 bool
 pa_shard_init(tsdn_t *tsdn, pa_shard_t *shard, base_t *base, unsigned ind,
-    pa_shard_stats_t *stats) {
+    pa_shard_stats_t *stats, malloc_mutex_t *stats_mtx) {
 	/* This will change eventually, but for now it should hold. */
 	assert(base_ind_get(base) == ind);
 	/*
@@ -44,6 +44,7 @@ pa_shard_init(tsdn_t *tsdn, pa_shard_t *shard, base_t *base, unsigned ind,
 
 	atomic_store_zu(&shard->extent_sn_next, 0, ATOMIC_RELAXED);
 
+	shard->stats_mtx = stats_mtx;
 	shard->stats = stats;
 	memset(shard->stats, 0, sizeof(*shard->stats));