diff --git a/CMakeLists.txt b/CMakeLists.txt
index a69b7a40..763bb0fd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -163,6 +163,8 @@ function(set_target_common_gns_properties TGT)
 		target_compile_definitions(${TGT} PUBLIC OSX)
 	elseif(CMAKE_SYSTEM_NAME MATCHES FreeBSD)
 		target_compile_definitions(${TGT} PUBLIC FREEBSD)
+	elseif(CMAKE_SYSTEM_NAME MATCHES OpenBSD)
+		target_compile_definitions(${TGT} PUBLIC OPENBSD)
 	elseif(CMAKE_SYSTEM_NAME MATCHES Windows)
 		target_compile_definitions(${TGT} PUBLIC _WINDOWS)
 		if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
diff --git a/include/steam/steamclientpublic.h b/include/steam/steamclientpublic.h
index 2bd66253..f3d6ca79 100644
--- a/include/steam/steamclientpublic.h
+++ b/include/steam/steamclientpublic.h
@@ -1157,7 +1157,7 @@ enum ESteamIPv6ConnectivityState
 // Define compile time assert macros to let us validate the structure sizes.
 #define VALVE_COMPILE_TIME_ASSERT( pred ) typedef char compile_time_assert_type[(pred) ? 1 : -1];
 
-#if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__)
+#if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || defined(__OpenBSD__)
 // The 32-bit version of gcc has the alignment requirement for uint64 and double set to
 // 4 meaning that even with #pragma pack(8) these types will only be four-byte aligned.
 // The 64-bit version of gcc has the alignment requirement for these types set to
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 26e09994..b9c3fde2 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -310,6 +310,8 @@ macro(set_clientlib_target_properties GNS_TARGET)
 		#endif()
 	elseif(CMAKE_SYSTEM_NAME MATCHES FreeBSD)
 
+	elseif(CMAKE_SYSTEM_NAME MATCHES OpenBSD)
+
 	elseif(CMAKE_SYSTEM_NAME MATCHES Windows)
 		if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
 			get_target_property(TARGET_TYPE ${GNS_TARGET} TYPE)
diff --git a/src/public/minbase/minbase_identify.h b/src/public/minbase/minbase_identify.h
index 4cdf0249..8c9f9c59 100644
--- a/src/public/minbase/minbase_identify.h
+++ b/src/public/minbase/minbase_identify.h
@@ -169,6 +169,9 @@
 #elif defined(__FreeBSD__)
 	#define IsFreeBSD() true
 	#define IsPosix() true
+#elif defined(__OpenBSD__)
+	#define IsOpenBSD() true
+	#define IsPosix() true
 #elif defined( _POSIX_VERSION ) || defined( POSIX ) || defined( VALVE_POSIX )
 	#define IsPosix() true
 #else
@@ -235,6 +238,9 @@
 #ifndef IsFreeBSD
 	#define IsFreeBSD() false
 #endif
+#ifndef IsOpenBSD
+	#define IsOpenBSD() false
+#endif
 
 // Detect ARM
 #ifndef IsARM
diff --git a/src/public/minbase/minbase_types.h b/src/public/minbase/minbase_types.h
index 0f35c5a0..27c9dc7b 100644
--- a/src/public/minbase/minbase_types.h
+++ b/src/public/minbase/minbase_types.h
@@ -75,7 +75,7 @@ typedef uint32 uint32_t;
 // NOTE: int64_t must match the compiler stdint.h definition
 // and so may not match the Steam int64.  Mixing the two is
 // error-prone so always use the Steam non-_t types in Steam code.
-#if defined(COMPILER_GCC) && defined(PLATFORM_64BITS) && !defined(__MINGW32__) && !IsOSX() && !(defined(IOS) || defined(TVOS))
+#if defined(COMPILER_GCC) && defined(PLATFORM_64BITS) && !defined(__MINGW32__) && !IsOSX() && !IsIOS() && !IsTVOS() && !IsOpenBSD()
 #define INT64_DIFFERENT_FROM_INT64_T 1
 typedef long int int64_t;
 typedef unsigned long int uint64_t;
diff --git a/src/public/tier0/platform_sockets.h b/src/public/tier0/platform_sockets.h
index 1d33955f..917bf171 100644
--- a/src/public/tier0/platform_sockets.h
+++ b/src/public/tier0/platform_sockets.h
@@ -145,6 +145,14 @@ typedef char SteamNetworkingErrMsg[ 1024 ];
 		// Does this work?  If somebody who uses FreeBSD
 		// wants to test, I would appreciate it!
 		#define PlatformSupportsRecvTOS() false
+	#elif defined(__OpenBSD__)
+
+		// OpenBSD provides kqueue, but we don't support it, so just use old-school poll()
+		#define USE_POLL
+
+		// Does this work?  If somebody who uses OpenBSD
+		// wants to test, I would appreciate it!
+		#define PlatformSupportsRecvTOS() false
 	#else
 		#define USE_EPOLL
 		#include <sys/epoll.h>
diff --git a/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp b/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
index a2645465..2558e43f 100644
--- a/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
+++ b/src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp
@@ -2454,8 +2454,10 @@ const char *CSteamNetworkingUtils::GetPlatformString()
 		return "windows";
 	#elif IsLinux()
 		return "linux";
-	#elif defined( FREEBSD ) || defined( __FreeBSD__ )
+	#elif IsFreeBSD()
 		return "freebsd";
+	#elif IsOpenBSD()
+		return "openbsd";
 	#else
 		#error "Unknown platform"
 	#endif
diff --git a/src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp b/src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp
index 0011cd84..d535e58a 100644
--- a/src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp
+++ b/src/steamnetworkingsockets/clientlib/steamnetworkingsockets_lowlevel.cpp
@@ -4289,7 +4289,11 @@ bool ResolveHostname( const char* pszHostname, CUtlVector< SteamNetworkingIPAddr
 
 	addrinfo hints;
 	V_memset( &hints, 0, sizeof( hints ) );
+#ifdef AI_V4MAPPED
 	hints.ai_flags = AI_V4MAPPED | AI_ADDRCONFIG;
+#else
+	hints.ai_flags = AI_ADDRCONFIG;
+#endif
 	hints.ai_family = AF_UNSPEC;
 	hints.ai_socktype = 0;
 	hints.ai_protocol = 0;
diff --git a/src/tier0/dbg.cpp b/src/tier0/dbg.cpp
index dd31cc38..9038e235 100644
--- a/src/tier0/dbg.cpp
+++ b/src/tier0/dbg.cpp
@@ -86,7 +86,7 @@ bool Plat_IsInDebugSession()
 	return (nTracePid != 0);
 #elif IsPlaystation()
 	// NDA material
-#elif IsNintendoSwitch()
+#elif IsNintendoSwitch() || IsOpenBSD()
 	return false;
 #else
 	#error "HALP"