diff --git a/util/genbuild_h/genbuild_h.sh b/util/genbuild_h/genbuild_h.sh
index b161dff..55a3b85 100755
--- a/util/genbuild_h/genbuild_h.sh
+++ b/util/genbuild_h/genbuild_h.sh
@@ -31,6 +31,16 @@
 	DATE=$(date +%s)
 fi
 
+our_date() {
+case $(uname) in
+NetBSD|OpenBSD|DragonFly|FreeBSD)
+	TZ=UTC date -r $1 $2
+	;;
+*)
+	TZ=UTC date -d @$1 $2
+esac
+}
+
 #Print out the information that goes into build.h
 printf "/* build system definitions (autogenerated) */\n"
 printf "#ifndef __BUILD_H\n"
@@ -43,12 +53,12 @@
 printf "#define COREBOOT_ORIGIN_GIT_REVISION \"$GITREV\"\n"
 
 printf "#define COREBOOT_EXTRA_VERSION \"%s\"\n" "$COREBOOT_EXTRA_VERSION"
-printf "#define COREBOOT_BUILD \"%s\"\n" "$(LANG= TZ=UTC date -d @$DATE)"
-printf "#define COREBOOT_BUILD_YEAR_BCD 0x%s\n" "$(TZ=UTC date -d @$DATE +%y)"
-printf "#define COREBOOT_BUILD_MONTH_BCD 0x%s\n" "$(TZ=UTC date -d @$DATE +%m)"
-printf "#define COREBOOT_BUILD_DAY_BCD 0x%s\n" "$(TZ=UTC date -d @$DATE +%d)"
-printf "#define COREBOOT_BUILD_WEEKDAY_BCD 0x%s\n" "$(TZ=UTC date -d @$DATE +%w)"
-printf "#define COREBOOT_DMI_DATE \"%s\"\n" "$(TZ=UTC date -d @$DATE +%m/%d/%Y)"
+printf "#define COREBOOT_BUILD \"$(LANG= our_date "$DATE")\"\n"
+printf "#define COREBOOT_BUILD_YEAR_BCD 0x$(our_date "$DATE" +%y)\n"
+printf "#define COREBOOT_BUILD_MONTH_BCD 0x$(our_date "$DATE" +%m)\n"
+printf "#define COREBOOT_BUILD_DAY_BCD 0x$(our_date "$DATE" +%d)\n"
+printf "#define COREBOOT_BUILD_WEEKDAY_BCD 0x$(our_date "$DATE" +%w)\n"
+printf "#define COREBOOT_DMI_DATE \"$(our_date "$DATE" +%m/%d/%Y)\"\n"
 printf "\n"
-printf "#define COREBOOT_COMPILE_TIME \"%s\"\n" "$(TZ=UTC date -d @$DATE +%T)"
+printf "#define COREBOOT_COMPILE_TIME \"$(our_date "$DATE" +%T)\"\n"
 printf "#endif\n"