diff --git a/build/jam/BuildSetup b/build/jam/BuildSetup
index 8b73fa6..ea7ca04 100644
--- a/build/jam/BuildSetup
+++ b/build/jam/BuildSetup
@@ -371,6 +371,7 @@ switch $(HOST_PLATFORM) {
 	case linux		: hostDebugFlags ?= -ggdb ;
 	case freebsd	: hostDebugFlags ?= -ggdb ;
 	case darwin		: hostDebugFlags ?= -ggdb ;
+	case openbsd	: hostDebugFlags ?= -ggdb ;
 	case *			: hostDebugFlags ?= -g ;
 }
 
@@ -586,7 +587,7 @@ HOST_BE_API_C++FLAGS = ;
 # platform, e.g. containing missing POSIX/GNU headers.
 HOST_HDRS += [ FDirName $(HAIKU_TOP) headers build host $(HOST_PLATFORM) ] ;
 
-if $(HOST_PLATFORM) = freebsd {
+if $(HOST_PLATFORM) = freebsd || $(HOST_PLATFORM) = openbsd {
 	# FreeBSD's gcc doesn't include /usr/local/* in its search paths,
 	# though that's where most things from ports wind up being installed.
 	HOST_HDRS += /usr/local/include ;
@@ -743,6 +744,7 @@ switch $(TARGET_PLATFORM) {
 	case linux		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LINUX ;
 	case freebsd	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_FREEBSD ;
 	case darwin		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_DARWIN ;
+	case openbsd	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_OPENBSD ;
 	case cygwin		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_CYGWIN ;
 	case sunos		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_SUNOS ;
 	case libbe_test	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LIBBE_TEST ;
@@ -757,6 +759,7 @@ switch $(HOST_PLATFORM) {
 	case linux		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_LINUX ;
 	case freebsd	: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_FREEBSD ;
 	case darwin		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_DARWIN ;
+	case openbsd	: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_OPENBSD ;
 	case cygwin		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_CYGWIN ;
 	case sunos		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_SUNOS ;
 }
diff --git a/build/scripts/build_cross_tools_gcc4 b/build/scripts/build_cross_tools_gcc4
index ea778e3..8243cf4 100755
--- a/build/scripts/build_cross_tools_gcc4
+++ b/build/scripts/build_cross_tools_gcc4
@@ -199,7 +199,7 @@ cd "$gccObjDir"
 CFLAGS="-O2" CXXFLAGS="-O2" "$gccSourceDir/configure" \
 	--prefix="$installDir" $buildHostSpec --target=$haikuMachine \
 	--disable-nls --disable-shared --with-system-zlib \
-	--enable-languages=c,c++ --enable-lto --enable-frame-pointer \
+	--enable-languages=c,c++ --disable-lto --enable-frame-pointer \
 	--with-sysroot="$sysrootDir" \
 	$gccConfigureArgs \
 	|| exit 1
diff --git a/headers/build/BeOSBuildCompatibility.h b/headers/build/BeOSBuildCompatibility.h
index 95c00d0..4f0f07f 100644
--- a/headers/build/BeOSBuildCompatibility.h
+++ b/headers/build/BeOSBuildCompatibility.h
@@ -51,7 +51,9 @@ extern size_t   strlcpy(char* dest, const char* source, size_t length);
 extern size_t	strlcat(char* dest, const char* source, size_t length);
 #endif
 
-#if defined(HAIKU_HOST_PLATFORM_FREEBSD) || defined(HAIKU_HOST_PLATFORM_DARWIN)
+#if defined(HAIKU_HOST_PLATFORM_FREEBSD) \
+	|| defined(HAIKU_HOST_PLATFORM_DARWIN) \
+	|| defined(HAIKU_HOST_PLATFORM_OPENBSD)
 extern size_t	strnlen(const char* string, size_t length);
 #endif
 
diff --git a/src/build/libroot/errors.cpp b/src/build/libroot/errors.cpp
index e0691a9..34a34ca 100644
--- a/src/build/libroot/errors.cpp
+++ b/src/build/libroot/errors.cpp
@@ -75,18 +75,24 @@ init_error_map()
 	ADD_ERROR(EOPNOTSUPP);
 	ADD_ERROR(ENOTSOCK);
 	ADD_ERROR(EHOSTDOWN);
-	ADD_ERROR(EBADMSG);
+	#ifdef EBADMSG
+		ADD_ERROR(EBADMSG);
+	#endif
 	#ifdef ECANCELED
 		ADD_ERROR(ECANCELED);
 	#endif
 	ADD_ERROR(EDESTADDRREQ);
 	ADD_ERROR(EDQUOT);
 	ADD_ERROR(EIDRM);
-	ADD_ERROR(EMULTIHOP);
+	#ifdef EMULTIHOP
+		ADD_ERROR(EMULTIHOP);
+	#endif
 	#ifdef ENODATA
 		ADD_ERROR(ENODATA);
 	#endif
-	ADD_ERROR(ENOLINK);
+	#ifdef ENOLINK
+		ADD_ERROR(ENOLINK);
+	#endif
 	#ifdef ENOSR
 		ADD_ERROR(ENOSR);
 	#endif
@@ -94,7 +100,9 @@ init_error_map()
 		ADD_ERROR(ENOSTR);
 	#endif
 	ADD_ERROR(ENOTSUP);
-	ADD_ERROR(EPROTO);
+	#ifdef EPROTO
+		ADD_ERROR(EPROTO);
+	#endif
 	#ifdef ETIME
 		ADD_ERROR(ETIME);
 	#endif
diff --git a/src/build/libsolv/Jamfile b/src/build/libsolv/Jamfile
index 9f3f9fa..0309800 100644
--- a/src/build/libsolv/Jamfile
+++ b/src/build/libsolv/Jamfile
@@ -30,6 +30,8 @@ switch $(HOST_PLATFORM) {
 		DEFINES += HAVE_FOPENCOOKIE ;
 	case freebsd :
 		DEFINES += HAVE_FUNOPEN ;
+	case openbsd :
+		DEFINES += HAVE_FUNOPEN ;
 	case darwin :
 		DEFINES += HAVE_FUNOPEN HAVE_QSORT_R ;
 	case * :
diff --git a/src/tools/fs_shell/unistd.cpp b/src/tools/fs_shell/unistd.cpp
index bcc5bcd..b4f8acc 100644
--- a/src/tools/fs_shell/unistd.cpp
+++ b/src/tools/fs_shell/unistd.cpp
@@ -21,7 +21,8 @@
 #	include <Drivers.h>
 #else
 #	if defined(HAIKU_HOST_PLATFORM_FREEBSD) \
-		|| defined(HAIKU_HOST_PLATFORM_DARWIN)
+		|| defined(HAIKU_HOST_PLATFORM_DARWIN) \
+		|| defined(HAIKU_HOST_PLATFORM_OPENBSD)
 #		include <sys/ioctl.h>
 #		include <sys/stat.h>
 #		include <sys/disk.h>