diff --git a/Makefile.in b/Makefile.in
index c9bd95a3..31a9ceaa 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -169,6 +169,7 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/base.c \
 	$(srcroot)test/unit/bitmap.c \
 	$(srcroot)test/unit/bit_util.c \
+	$(srcroot)test/unit/binshard.c \
 	$(srcroot)test/unit/ckh.c \
 	$(srcroot)test/unit/decay.c \
 	$(srcroot)test/unit/div.c \
diff --git a/test/unit/binshard.c b/test/unit/binshard.c
new file mode 100644
index 00000000..829ba433
--- /dev/null
+++ b/test/unit/binshard.c
@@ -0,0 +1,103 @@
+#include "test/jemalloc_test.h"
+
+/* Config -- "narenas:1,bin_shards:1-160:16|129-512:4|256-256:8" */
+
+static void *
+thd_start(void *varg) {
+	void *ptr, *ptr2;
+	extent_t *extent;
+	unsigned shard1, shard2;
+
+	tsdn_t *tsdn = tsdn_fetch();
+	/* Try triggering allocations from sharded bins. */
+	for (unsigned i = 0; i < 1024; i++) {
+		ptr = mallocx(1, MALLOCX_TCACHE_NONE);
+		ptr2 = mallocx(129, MALLOCX_TCACHE_NONE);
+
+		extent = iealloc(tsdn, ptr);
+		shard1 = extent_binshard_get(extent);
+		dallocx(ptr, 0);
+		assert_u_lt(shard1, 16, "Unexpected bin shard used");
+
+		extent = iealloc(tsdn, ptr2);
+		shard2 = extent_binshard_get(extent);
+		dallocx(ptr2, 0);
+		assert_u_lt(shard2, 4, "Unexpected bin shard used");
+
+		if (shard1 > 0 || shard2 > 0) {
+			/* Triggered sharded bin usage. */
+			return (void *)(uintptr_t)shard1;
+		}
+	}
+
+	return NULL;
+}
+
+TEST_BEGIN(test_bin_shard_mt) {
+#define NTHREADS 16
+	thd_t thds[NTHREADS];
+	unsigned i;
+	for (i = 0; i < NTHREADS; i++) {
+		thd_create(&thds[i], thd_start, NULL);
+	}
+	bool sharded = false;
+	for (i = 0; i < NTHREADS; i++) {
+		void *ret;
+		thd_join(thds[i], &ret);
+		if (ret != NULL) {
+			sharded = true;
+		}
+	}
+	assert_b_eq(sharded, true, "Did not find sharded bins");
+}
+TEST_END
+
+TEST_BEGIN(test_bin_shard) {
+	unsigned nbins, i;
+	size_t mib[4], mib2[4];
+	size_t miblen, miblen2, len;
+
+	len = sizeof(nbins);
+	assert_d_eq(mallctl("arenas.nbins", (void *)&nbins, &len, NULL, 0), 0,
+	    "Unexpected mallctl() failure");
+
+	miblen = 4;
+	assert_d_eq(mallctlnametomib("arenas.bin.0.nshards", mib, &miblen), 0,
+	    "Unexpected mallctlnametomib() failure");
+	miblen2 = 4;
+	assert_d_eq(mallctlnametomib("arenas.bin.0.size", mib2, &miblen2), 0,
+	    "Unexpected mallctlnametomib() failure");
+
+	for (i = 0; i < nbins; i++) {
+		uint32_t nshards;
+		size_t size, sz1, sz2;
+
+		mib[2] = i;
+		sz1 = sizeof(nshards);
+		assert_d_eq(mallctlbymib(mib, miblen, (void *)&nshards, &sz1,
+		    NULL, 0), 0, "Unexpected mallctlbymib() failure");
+
+		mib2[2] = i;
+		sz2 = sizeof(size);
+		assert_d_eq(mallctlbymib(mib2, miblen2, (void *)&size, &sz2,
+		    NULL, 0), 0, "Unexpected mallctlbymib() failure");
+
+		if (size >= 1 && size <= 128) {
+			assert_u_eq(nshards, 16, "Unexpected nshards");
+		} else if (size == 256) {
+			assert_u_eq(nshards, 8, "Unexpected nshards");
+		} else if (size > 128 && size <= 512) {
+			assert_u_eq(nshards, 4, "Unexpected nshards");
+		} else {
+			assert_u_eq(nshards, 1, "Unexpected nshards");
+		}
+	}
+}
+TEST_END
+
+int
+main(void) {
+	return test_no_reentrancy(
+	    test_bin_shard,
+	    test_bin_shard_mt);
+}
diff --git a/test/unit/binshard.sh b/test/unit/binshard.sh
new file mode 100644
index 00000000..c1d58c88
--- /dev/null
+++ b/test/unit/binshard.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+export MALLOC_CONF="narenas:1,bin_shards:1-160:16|129-512:4|256-256:8"