diff --git a/lib/mosquitto_internal.h b/lib/mosquitto_internal.h
index 8b862638..cd3d69d2 100644
--- a/lib/mosquitto_internal.h
+++ b/lib/mosquitto_internal.h
@@ -361,7 +361,8 @@ struct mosquitto {
 	struct mosquitto__packet *out_packet_last;
 	struct mosquitto__subleaf **subs;
 	char *auth_method;
-	int sub_count;
+	int subs_capacity; /* allocated size of the subs instance */
+	int subs_count; /* number of currently active subscriptions */
 #  ifndef WITH_EPOLL
 	int pollfd_index;
 #  endif
@@ -447,4 +448,3 @@ struct mosquitto {
 void do_client_disconnect(struct mosquitto *mosq, int reason_code, const mosquitto_property *properties);
 
 #endif
-
diff --git a/src/handle_connect.c b/src/handle_connect.c
index 2abc4155..42f7900b 100644
--- a/src/handle_connect.c
+++ b/src/handle_connect.c
@@ -164,11 +164,13 @@ int connect__on_authorised(struct mosquitto *context, void *auth_data_out, uint1
 			}
 			context->subs = found_context->subs;
 			found_context->subs = NULL;
-			context->sub_count = found_context->sub_count;
-			found_context->sub_count = 0;
+			context->subs_capacity = found_context->subs_capacity;
+			context->subs_count = found_context->subs_count;
+			found_context->subs_capacity = 0;
+			found_context->subs_count = 0;
 			context->last_mid = found_context->last_mid;
 
-			for(i=0; i<context->sub_count; i++){
+			for(i=0; i<context->subs_capacity; i++){
 				if(context->subs[i]){
 					leaf = context->subs[i]->hier->subs;
 					while(leaf){
diff --git a/src/plugin_public.c b/src/plugin_public.c
index 5a0610e2..9b62e887 100644
--- a/src/plugin_public.c
+++ b/src/plugin_public.c
@@ -172,7 +172,7 @@ BROKER_EXPORT int mosquitto_client_protocol_version(const struct mosquitto *clie
 BROKER_EXPORT int mosquitto_client_sub_count(const struct mosquitto *client)
 {
 	if(client){
-		return client->sub_count;
+		return client->subs_count;
 	}else{
 		return 0;
 	}
@@ -371,7 +371,7 @@ static void check_subscription_acls(struct mosquitto *context)
 	int rc;
 	uint8_t reason;
 
-	for(i=0; i<context->sub_count; i++){
+	for(i=0; i<context->subs_capacity; i++){
 		if(context->subs[i] == NULL){
 			continue;
 		}
diff --git a/src/subs.c b/src/subs.c
index daf1eb8e..33c118c4 100644
--- a/src/subs.c
+++ b/src/subs.c
@@ -232,23 +232,25 @@ static int sub__add_shared(struct mosquitto *context, const char *sub, uint8_t q
 		newleaf->shared = shared;
 
 		bool assigned = false;
-		for(i=0; i<context->sub_count; i++){
+		for(i=0; i<context->subs_capacity; i++){
 			if(!context->subs[i]){
 				context->subs[i] = newleaf;
+				context->subs_count++;
 				assigned = true;
 				break;
 			}
 		}
 		if(assigned == false){
-			subs = mosquitto__realloc(context->subs, sizeof(struct mosquitto__subleaf *)*(size_t)(context->sub_count + 1));
+			subs = mosquitto__realloc(context->subs, sizeof(struct mosquitto__subleaf *)*(size_t)(context->subs_capacity + 1));
 			if(!subs){
 				sub__remove_shared_leaf(subhier, shared, newleaf);
 				mosquitto__FREE(newleaf);
 				return MOSQ_ERR_NOMEM;
 			}
 			context->subs = subs;
-			context->sub_count++;
-			context->subs[context->sub_count-1] = newleaf;
+			context->subs_capacity++;
+			context->subs_count++;
+			context->subs[context->subs_capacity-1] = newleaf;
 		}
 #ifdef WITH_SYS_TREE
 		db.shared_subscription_count++;
@@ -282,23 +284,25 @@ static int sub__add_normal(struct mosquitto *context, const char *sub, uint8_t q
 		newleaf->shared = NULL;
 
 		bool assigned = false;
-		for(i=0; i<context->sub_count; i++){
+		for(i=0; i<context->subs_capacity; i++){
 			if(!context->subs[i]){
 				context->subs[i] = newleaf;
+				context->subs_count++;
 				assigned = true;
 				break;
 			}
 		}
 		if(assigned == false){
-			subs = mosquitto__realloc(context->subs, sizeof(struct mosquitto__subleaf *)*(size_t)(context->sub_count + 1));
+			subs = mosquitto__realloc(context->subs, sizeof(struct mosquitto__subleaf *)*(size_t)(context->subs_capacity + 1));
 			if(!subs){
 				DL_DELETE(subhier->subs, newleaf);
 				mosquitto__FREE(newleaf);
 				return MOSQ_ERR_NOMEM;
 			}
 			context->subs = subs;
-			context->sub_count++;
-			context->subs[context->sub_count-1] = newleaf;
+			context->subs_capacity++;
+			context->subs_count++;
+			context->subs[context->subs_capacity-1] = newleaf;
 		}
 #ifdef WITH_SYS_TREE
 		db.subscription_count++;
@@ -367,8 +371,9 @@ static int sub__remove_normal(struct mosquitto *context, struct mosquitto__subhi
 			 * It would be nice to be able to use the reference directly,
 			 * but that would involve keeping a copy of the topic string in
 			 * each subleaf. Might be worth considering though. */
-			for(i=0; i<context->sub_count; i++){
+			for(i=0; i<context->subs_capacity; i++){
 				if(context->subs[i] == leaf){
+					context->subs_count--;
 					mosquitto__FREE(context->subs[i]);
 					break;
 				}
@@ -402,8 +407,9 @@ static int sub__remove_shared(struct mosquitto *context, struct mosquitto__subhi
 				* It would be nice to be able to use the reference directly,
 				* but that would involve keeping a copy of the topic string in
 				* each subleaf. Might be worth considering though. */
-				for(i=0; i<context->sub_count; i++){
+				for(i=0; i<context->subs_capacity; i++){
 					if(context->subs[i] == leaf){
+						context->subs_count--;
 						mosquitto__FREE(context->subs[i]);
 						break;
 					}
@@ -680,7 +686,7 @@ int sub__clean_session(struct mosquitto *context)
 	struct mosquitto__subleaf *leaf;
 	struct mosquitto__subhier *hier;
 
-	for(i=0; i<context->sub_count; i++){
+	for(i=0; i<context->subs_capacity; i++){
 		if(context->subs[i] == NULL || context->subs[i]->hier == NULL){
 			continue;
 		}
@@ -726,7 +732,8 @@ int sub__clean_session(struct mosquitto *context)
 		}
 	}
 	mosquitto__FREE(context->subs);
-	context->sub_count = 0;
+	context->subs_capacity = 0;
+	context->subs_count = 0;
 
 	return MOSQ_ERR_SUCCESS;
 }