diff --git a/src/main.cpp b/src/main.cpp
index f6b0d03..dba5f23 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -18,10 +18,11 @@ struct month_info {
 int main(int argc, char *argv[]) {
 	unsigned int distance = 2'000;
 	std::string fire_dir = "fires";
+	unsigned int wc = 0;
 	std::filesystem::path out_dir = "out";
 	auto do_sort = false;
 	int c;
-	while ((c = getopt(argc, argv, "d:f:o:s")) != -1) {
+	while ((c = getopt(argc, argv, "d:f:j:o:s")) != -1) {
 		switch (c) {
 		case 'd':
 			distance = atoi(optarg);
@@ -29,6 +30,9 @@ int main(int argc, char *argv[]) {
 		case 'f':
 			fire_dir = optarg;
 			break;
+		case 'j':
+			wc = atoi(optarg);
+			break;
 		case 'o':
 			out_dir = optarg;
 			break;
@@ -47,6 +51,15 @@ int main(int argc, char *argv[]) {
 		}
 	}
 
+	if (wc == 0) {
+		wc = std::thread::hardware_concurrency();
+		if (wc == 0) {
+			wc = 1;
+		} else if (wc > 1) {
+			wc--;
+		}
+	}
+
 	char *res_loc;
 	switch (argc - optind) {
 	case 0: {
@@ -166,12 +179,6 @@ int main(int argc, char *argv[]) {
 	auto it = all_fires.begin();
 	unsigned int n_done = 0;
 	std::mutex it_lock;
-	auto wc = std::thread::hardware_concurrency();
-	if (wc == 0) {
-		wc = 1;
-	} else if (wc > 1) {
-		wc--;
-	}
 	std::cout << "Starting " << wc << " worker threads..." << std::endl;
 	for (unsigned int w = 1; w <= wc; w++) {
 		workers.push_back(std::thread([&it, &n_done, &it_lock, &all_fires,