diff --git a/UI/CMakeLists.txt b/UI/CMakeLists.txt
index 256bb6646..1206f2bef 100644
--- a/UI/CMakeLists.txt
+++ b/UI/CMakeLists.txt
@@ -132,6 +132,11 @@ elseif(UNIX)
 
         set(obs_PLATFORM_LIBRARIES
                 Qt5::X11Extras)
+
+	if("${CMAKE_SYSTEM_NAME}" MATCHES "FreeBSD")
+		list(APPEND obs_PLATFORM_LIBRARIES
+			procstat)
+	endif()
 endif()
 
 if(BROWSER_AVAILABLE_INTERNAL)
diff --git a/UI/obs-app.cpp b/UI/obs-app.cpp
index bc0fcabc4..93098fa11 100644
--- a/UI/obs-app.cpp
+++ b/UI/obs-app.cpp
@@ -1950,6 +1950,8 @@ static int run_program(fstream &logFile, int argc, char *argv[])
 		CheckAppWithSameBundleID(already_running);
 #elif defined(__linux__)
 		RunningInstanceCheck(already_running);
+#elif defined(__FreeBSD__) || defined(__DragonFly__)
+		PIDFileCheck(already_running);
 #endif
 
 		if (!already_running) {
diff --git a/UI/platform-x11.cpp b/UI/platform-x11.cpp
index f74e0f43b..dd4a9c321 100644
--- a/UI/platform-x11.cpp
+++ b/UI/platform-x11.cpp
@@ -35,6 +35,17 @@
 #include <stdio.h>
 #include <sys/un.h>
 #endif
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+#include <sys/param.h>
+#include <fcntl.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#include <libprocstat.h>
+
+#include <condition_variable>
+#include <mutex>
+#include <thread>
+#endif
 
 using namespace std;
 
@@ -90,6 +101,75 @@ void RunningInstanceCheck(bool &already_running)
 	fclose(fp);
 }
 #endif
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+struct RunOnce {
+	std::thread thr;
+	static const char *thr_name;
+	std::condition_variable cv;
+	std::condition_variable wait_cv;
+	std::mutex mtx;
+	bool exiting = false;
+	bool name_changed = false;
+
+	void thr_proc()
+	{
+		std::unique_lock<std::mutex> lk(mtx);
+		pthread_setname_np(pthread_self(), thr_name);
+		name_changed = true;
+		wait_cv.notify_all();
+		cv.wait(lk, [this]() { return exiting; });
+	}
+
+	~RunOnce()
+	{
+		if (thr.joinable()) {
+			std::unique_lock<std::mutex> lk(mtx);
+			exiting = true;
+			cv.notify_one();
+			lk.unlock();
+			thr.join();
+		}
+	}
+} RO;
+const char *RunOnce::thr_name = "OBS runonce";
+
+void PIDFileCheck(bool &already_running)
+{
+	std::string tmpfile_name =
+		"/tmp/obs-studio.lock." + to_string(geteuid());
+	int fd = open(tmpfile_name.c_str(), O_RDWR | O_CREAT | O_EXLOCK, 0600);
+	if (fd == -1) {
+		already_running = true;
+		return;
+	}
+
+	already_running = false;
+
+	procstat *ps = procstat_open_sysctl();
+	unsigned int count;
+	auto procs = procstat_getprocs(ps, KERN_PROC_UID | KERN_PROC_INC_THREAD,
+				       geteuid(), &count);
+	for (unsigned int i = 0; i < count; i++) {
+		if (!strncmp(procs[i].ki_tdname, RunOnce::thr_name,
+			     sizeof(procs[i].ki_tdname))) {
+			already_running = true;
+			break;
+		}
+	}
+	procstat_freeprocs(ps, procs);
+	procstat_close(ps);
+
+	RO.thr = std::thread(std::mem_fn(&RunOnce::thr_proc), &RO);
+
+	{
+		std::unique_lock<std::mutex> lk(RO.mtx);
+		RO.wait_cv.wait(lk, []() { return RO.name_changed; });
+	}
+
+	unlink(tmpfile_name.c_str());
+	close(fd);
+}
+#endif
 
 static inline bool check_path(const char *data, const char *path,
 			      string &output)
diff --git a/UI/platform.hpp b/UI/platform.hpp
index f8717cb43..7e7d47ed1 100644
--- a/UI/platform.hpp
+++ b/UI/platform.hpp
@@ -73,3 +73,6 @@ void CheckAppWithSameBundleID(bool &already_running);
 #ifdef __linux__
 void RunningInstanceCheck(bool &already_running);
 #endif
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+void PIDFileCheck(bool &already_running);
+#endif