diff --git a/regamedll/CMakeLists.txt b/regamedll/CMakeLists.txt
index b1166d023..95fba9952 100644
--- a/regamedll/CMakeLists.txt
+++ b/regamedll/CMakeLists.txt
@@ -143,6 +143,10 @@ endif()
 if (NOT DEBUG AND NOT ANDROID AND NOT APPLE)
 	set(LINK_FLAGS "${LINK_FLAGS} \
 		-Wl,-gc-sections -Wl,--version-script=\"${PROJECT_SOURCE_DIR}/../version_script.lds\"")
+	if (CMAKE_SYSTEM_NAME MATCHES "BSD|DragonFly")
+		# lld rejects version script entries for symbols not defined in the output (libstdc++-only names)
+		set(LINK_FLAGS "${LINK_FLAGS} -Wl,--undefined-version")
+	endif()
 endif()
 
 find_program(CCACHE_FOUND ccache)
diff --git a/regamedll/engine/osconfig.h b/regamedll/engine/osconfig.h
index 554b1d899..572f72474 100644
--- a/regamedll/engine/osconfig.h
+++ b/regamedll/engine/osconfig.h
@@ -89,7 +89,9 @@
 	#include <sys/time.h>
 	#include <sys/types.h>
 #if !defined(__APPLE__)
+	#if defined(__linux__)
 	#include <sys/sysinfo.h>
+	#endif
 #else
 	#include <sys/sysctl.h>
 #endif
diff --git a/regamedll/game_shared/counter.h b/regamedll/game_shared/counter.h
index 84f03ce8d..599097853 100644
--- a/regamedll/game_shared/counter.h
+++ b/regamedll/game_shared/counter.h
@@ -38,7 +38,7 @@
 	#include <sys/types.h>
 	#include <fcntl.h>
 	#include <unistd.h>
-	#ifdef __APPLE__
+	#ifndef __linux__
 		#include <limits.h>
 	#else
 		#include <linux/limits.h>
diff --git a/regamedll/public/tier0/platform.h b/regamedll/public/tier0/platform.h
index eaf294f5a..d5fa5334e 100644
--- a/regamedll/public/tier0/platform.h
+++ b/regamedll/public/tier0/platform.h
@@ -75,7 +75,7 @@
 // Can't use extern "C" when DLL exporting a global
 #define DLL_GLOBAL_EXPORT extern __declspec(dllexport)
 #define DLL_GLOBAL_IMPORT extern __declspec(dllimport)
-#elif defined __linux__ || defined __APPLE__
+#elif defined __linux__ || defined __APPLE__ || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__
 
 // Used for dll exporting and importing
 #define DLL_EXPORT extern "C"
diff --git a/regamedll/version/appversion.sh b/regamedll/version/appversion.sh
index 68c35862f..0bae28099 100755
--- a/regamedll/version/appversion.sh
+++ b/regamedll/version/appversion.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 init()
 {