diff --git a/include/spdk/nvmf.h b/include/spdk/nvmf.h
index 9f8a7f9a6..66462b403 100644
--- a/include/spdk/nvmf.h
+++ b/include/spdk/nvmf.h
@@ -66,6 +66,7 @@ struct spdk_nvmf_tgt_opts {
 	uint16_t max_qpairs_per_ctrlr;
 	uint32_t in_capsule_data_size;
 	uint32_t max_io_size;
+	uint32_t max_subsystems;
 };
 /**
  * Initialize the default value of opts.
diff --git a/lib/nvmf/ctrlr_discovery.c b/lib/nvmf/ctrlr_discovery.c
index 840da2f7b..a2fe5ec16 100644
--- a/lib/nvmf/ctrlr_discovery.c
+++ b/lib/nvmf/ctrlr_discovery.c
@@ -69,7 +69,7 @@ nvmf_update_discovery_log(struct spdk_nvmf_tgt *tgt)
 		return;
 	}
 
-	for (sid = 0; sid < tgt->max_sid; sid++) {
+	for (sid = 0; sid < tgt->opts.max_subsystems; sid++) {
 		subsystem = tgt->subsystems[sid];
 		if (subsystem == NULL) {
 			continue;
diff --git a/lib/nvmf/nvmf.c b/lib/nvmf/nvmf.c
index 554c7e6e3..823bc967c 100644
--- a/lib/nvmf/nvmf.c
+++ b/lib/nvmf/nvmf.c
@@ -46,12 +46,11 @@
 
 SPDK_LOG_REGISTER_COMPONENT("nvmf", SPDK_LOG_NVMF)
 
-#define MAX_SUBSYSTEMS 4
-
 #define SPDK_NVMF_DEFAULT_MAX_QUEUE_DEPTH 128
 #define SPDK_NVMF_DEFAULT_MAX_QPAIRS_PER_CTRLR 64
 #define SPDK_NVMF_DEFAULT_IN_CAPSULE_DATA_SIZE 4096
 #define SPDK_NVMF_DEFAULT_MAX_IO_SIZE 131072
+#define SPDK_NVMF_DEFAULT_MAX_SUBSYSTEMS 1024
 
 void
 spdk_nvmf_tgt_opts_init(struct spdk_nvmf_tgt_opts *opts)
@@ -60,6 +59,7 @@ spdk_nvmf_tgt_opts_init(struct spdk_nvmf_tgt_opts *opts)
 	opts->max_qpairs_per_ctrlr = SPDK_NVMF_DEFAULT_MAX_QPAIRS_PER_CTRLR;
 	opts->in_capsule_data_size = SPDK_NVMF_DEFAULT_IN_CAPSULE_DATA_SIZE;
 	opts->max_io_size = SPDK_NVMF_DEFAULT_MAX_IO_SIZE;
+	opts->max_subsystems = SPDK_NVMF_DEFAULT_MAX_SUBSYSTEMS;
 }
 
 static int
@@ -95,13 +95,13 @@ spdk_nvmf_tgt_create_poll_group(void *io_device, void *ctx_buf)
 		spdk_nvmf_poll_group_add_transport(group, transport);
 	}
 
-	group->num_sgroups = tgt->max_sid;
-	group->sgroups = calloc(group->num_sgroups, sizeof(struct spdk_nvmf_subsystem_poll_group));
+	group->num_sgroups = tgt->opts.max_subsystems;
+	group->sgroups = calloc(tgt->opts.max_subsystems, sizeof(struct spdk_nvmf_subsystem_poll_group));
 	if (!group->sgroups) {
 		return -1;
 	}
 
-	for (sid = 0; sid < group->num_sgroups; sid++) {
+	for (sid = 0; sid < tgt->opts.max_subsystems; sid++) {
 		struct spdk_nvmf_subsystem *subsystem;
 
 		subsystem = tgt->subsystems[sid];
@@ -168,10 +168,14 @@ spdk_nvmf_tgt_create(struct spdk_nvmf_tgt_opts *opts)
 	tgt->discovery_genctr = 0;
 	tgt->discovery_log_page = NULL;
 	tgt->discovery_log_page_size = 0;
-	tgt->subsystems = NULL;
-	tgt->max_sid = 0;
 	TAILQ_INIT(&tgt->transports);
 
+	tgt->subsystems = calloc(tgt->opts.max_subsystems, sizeof(struct spdk_nvmf_subsystem *));
+	if (!tgt->subsystems) {
+		free(tgt);
+		return NULL;
+	}
+
 	spdk_io_device_register(tgt,
 				spdk_nvmf_tgt_create_poll_group,
 				spdk_nvmf_tgt_destroy_poll_group,
@@ -198,7 +202,7 @@ spdk_nvmf_tgt_destroy(struct spdk_nvmf_tgt *tgt)
 	}
 
 	if (tgt->subsystems) {
-		for (i = 0; i < tgt->max_sid; i++) {
+		for (i = 0; i < tgt->opts.max_subsystems; i++) {
 			if (tgt->subsystems[i]) {
 				spdk_nvmf_subsystem_destroy(tgt->subsystems[i]);
 			}
@@ -311,7 +315,7 @@ spdk_nvmf_tgt_find_subsystem(struct spdk_nvmf_tgt *tgt, const char *subnqn)
 		return NULL;
 	}
 
-	for (sid = 0; sid < tgt->max_sid; sid++) {
+	for (sid = 0; sid < tgt->opts.max_subsystems; sid++) {
 		subsystem = tgt->subsystems[sid];
 		if (subsystem == NULL) {
 			continue;
@@ -445,21 +449,7 @@ poll_group_update_subsystem(struct spdk_nvmf_poll_group *group,
 
 	/* Make sure our poll group has memory for this subsystem allocated */
 	if (subsystem->id >= group->num_sgroups) {
-		void *buf;
-
-		buf = realloc(group->sgroups, (subsystem->id + 1) * sizeof(*sgroup));
-		if (!buf) {
-			return -ENOMEM;
-		}
-
-		group->sgroups = buf;
-
-		/* Zero out the newly allocated memory */
-		memset(&group->sgroups[group->num_sgroups],
-		       0,
-		       (subsystem->id + 1 - group->num_sgroups) * sizeof(group->sgroups[0]));
-
-		group->num_sgroups = subsystem->id + 1;
+		return -ENOMEM;
 	}
 
 	sgroup = &group->sgroups[subsystem->id];
@@ -630,10 +620,6 @@ spdk_nvmf_poll_group_resume_subsystem(struct spdk_nvmf_poll_group *group,
 		return rc;
 	}
 
-	/* poll_group_update_subsystem may realloc the sgroups array. We need
-	 * to do a new lookup to get the correct pointer. */
-	sgroup = &group->sgroups[subsystem->id];
-
 	sgroup->state = SPDK_NVMF_SUBSYSTEM_ACTIVE;
 
 	/* Release all queued requests */
diff --git a/lib/nvmf/nvmf_internal.h b/lib/nvmf/nvmf_internal.h
index 2945e205a..b8e9ef056 100644
--- a/lib/nvmf/nvmf_internal.h
+++ b/lib/nvmf/nvmf_internal.h
@@ -60,9 +60,8 @@ struct spdk_nvmf_tgt {
 
 	uint64_t				discovery_genctr;
 
-	/* Array of subsystem pointers of size max_sid indexed by sid */
+	/* Array of subsystem pointers of size max_subsystems indexed by sid */
 	struct spdk_nvmf_subsystem		**subsystems;
-	uint32_t				max_sid;
 
 	struct spdk_nvmf_discovery_log_page	*discovery_log_page;
 	size_t					discovery_log_page_size;
diff --git a/lib/nvmf/subsystem.c b/lib/nvmf/subsystem.c
index 3b70720a6..466f5aa85 100644
--- a/lib/nvmf/subsystem.c
+++ b/lib/nvmf/subsystem.c
@@ -253,21 +253,13 @@ spdk_nvmf_subsystem_create(struct spdk_nvmf_tgt *tgt,
 	}
 
 	/* Find a free subsystem id (sid) */
-	for (sid = 0; sid < tgt->max_sid; sid++) {
+	for (sid = 0; sid < tgt->opts.max_subsystems; sid++) {
 		if (tgt->subsystems[sid] == NULL) {
 			break;
 		}
 	}
-	if (sid == tgt->max_sid) {
-		struct spdk_nvmf_subsystem **subsys_array;
-		/* No free slots. Add more. */
-		tgt->max_sid++;
-		subsys_array = realloc(tgt->subsystems, tgt->max_sid * sizeof(struct spdk_nvmf_subsystem *));
-		if (!subsys_array) {
-			tgt->max_sid--;
-			return NULL;
-		}
-		tgt->subsystems = subsys_array;
+	if (sid >= tgt->opts.max_subsystems) {
+		return NULL;
 	}
 
 	subsystem = calloc(1, sizeof(struct spdk_nvmf_subsystem));
@@ -560,7 +552,7 @@ spdk_nvmf_subsystem_get_first(struct spdk_nvmf_tgt *tgt)
 	struct spdk_nvmf_subsystem	*subsystem;
 	uint32_t sid;
 
-	for (sid = 0; sid < tgt->max_sid; sid++) {
+	for (sid = 0; sid < tgt->opts.max_subsystems; sid++) {
 		subsystem = tgt->subsystems[sid];
 		if (subsystem) {
 			return subsystem;
@@ -582,7 +574,7 @@ spdk_nvmf_subsystem_get_next(struct spdk_nvmf_subsystem *subsystem)
 
 	tgt = subsystem->tgt;
 
-	for (sid = subsystem->id + 1; sid < tgt->max_sid; sid++) {
+	for (sid = subsystem->id + 1; sid < tgt->opts.max_subsystems; sid++) {
 		subsystem = tgt->subsystems[sid];
 		if (subsystem) {
 			return subsystem;
diff --git a/test/unit/lib/nvmf/ctrlr_discovery.c/ctrlr_discovery_ut.c b/test/unit/lib/nvmf/ctrlr_discovery.c/ctrlr_discovery_ut.c
index 22faad015..97633a80b 100644
--- a/test/unit/lib/nvmf/ctrlr_discovery.c/ctrlr_discovery_ut.c
+++ b/test/unit/lib/nvmf/ctrlr_discovery.c/ctrlr_discovery_ut.c
@@ -208,6 +208,10 @@ test_discovery_log(void)
 	struct spdk_nvmf_discovery_log_page_entry *entry;
 	struct spdk_nvme_transport_id trid = {};
 
+	tgt.opts.max_subsystems = 1024;
+	tgt.subsystems = calloc(tgt.opts.max_subsystems, sizeof(struct spdk_nvmf_subsystem *));
+	SPDK_CU_ASSERT_FATAL(tgt.subsystems != NULL);
+
 	/* Add one subsystem and verify that the discovery log contains it */
 	subsystem = spdk_nvmf_subsystem_create(&tgt, "nqn.2016-06.io.spdk:subsystem1",
 					       SPDK_NVMF_SUBTYPE_NVME, 0);
diff --git a/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c b/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
index b8395e08f..a08621974 100644
--- a/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
+++ b/test/unit/lib/nvmf/subsystem.c/subsystem_ut.c
@@ -243,6 +243,10 @@ test_spdk_nvmf_subsystem_add_ns(void)
 	struct spdk_nvmf_ns_opts ns_opts;
 	uint32_t nsid;
 
+	tgt.opts.max_subsystems = 1024;
+	tgt.subsystems = calloc(tgt.opts.max_subsystems, sizeof(struct spdk_nvmf_subsystem *));
+	SPDK_CU_ASSERT_FATAL(tgt.subsystems != NULL);
+
 	/* Allow NSID to be assigned automatically */
 	spdk_nvmf_ns_opts_get_defaults(&ns_opts, sizeof(ns_opts));
 	nsid = spdk_nvmf_subsystem_add_ns(&subsystem, &bdev1, &ns_opts, sizeof(ns_opts));
@@ -280,6 +284,7 @@ test_spdk_nvmf_subsystem_add_ns(void)
 	spdk_nvmf_subsystem_remove_ns(&subsystem, 5, subsystem_ns_remove_cb, NULL);
 
 	free(subsystem.ns);
+	free(tgt.subsystems);
 }
 
 static void
@@ -289,6 +294,10 @@ nvmf_test_create_subsystem(void)
 	char nqn[256];
 	struct spdk_nvmf_subsystem *subsystem;
 
+	tgt.opts.max_subsystems = 1024;
+	tgt.subsystems = calloc(tgt.opts.max_subsystems, sizeof(struct spdk_nvmf_subsystem *));
+	SPDK_CU_ASSERT_FATAL(tgt.subsystems != NULL);
+
 	snprintf(nqn, sizeof(nqn), "nqn.2016-06.io.spdk:subsystem1");
 	subsystem = spdk_nvmf_subsystem_create(&tgt, nqn, SPDK_NVMF_SUBTYPE_NVME, 0);
 	SPDK_CU_ASSERT_FATAL(subsystem != NULL);