diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -536,10 +536,17 @@
      CPPFLAGS="$CPPFLAGS -DMAC_OSX"
      OBJCXXFLAGS="$CXXFLAGS"
      ;;
+   *android*)
+     dnl make sure android stays above linux for hosts like *linux-android*
+     LEVELDB_TARGET_FLAGS="-DOS_ANDROID"
+     ;;
    *linux*)
      TARGET_OS=linux
      LEVELDB_TARGET_FLAGS="-DOS_LINUX"
      ;;
+   *kfreebsd*)
+     LEVELDB_TARGET_FLAGS="-DOS_KFREEBSD"
+     ;;
    *freebsd*)
      LEVELDB_TARGET_FLAGS="-DOS_FREEBSD"
      ;;
@@ -549,10 +556,17 @@
    *netbsd*)
      LEVELDB_TARGET_FLAGS="-DOS_NETBSD"
      ;;
+   *dragonfly*)
+     LEVELDB_TARGET_FLAGS="-DOS_DRAGONFLYBSD"
+     ;;
+   *solaris*)
+     LEVELDB_TARGET_FLAGS="-DOS_SOLARIS"
+     ;;
+   *hpux*)
+     LEVELDB_TARGET_FLAGS="-DOS_HPUX"
+     ;;
    *)
-     OTHER_OS=`echo ${host_os} | awk '{print toupper($0)}'`
-     AC_MSG_WARN([Guessing LevelDB OS as OS_${OTHER_OS}, please check whether this is correct, if not add an entry to configure.ac.])
-     LEVELDB_TARGET_FLAGS="-DOS_${OTHER_OS}"
+     AC_MSG_ERROR(Cannot build leveldb for $host. Please file a bug report.)
      ;;
 esac
 
diff --git a/src/leveldb/CMakeLists.txt b/src/leveldb/CMakeLists.txt
--- a/src/leveldb/CMakeLists.txt
+++ b/src/leveldb/CMakeLists.txt
@@ -101,6 +101,8 @@
 		set(LEVELDB_OS SOLARIS)
 	elseif(${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD")
 		set(LEVELDB_OS FREEBSD)
+	elseif(${CMAKE_SYSTEM_NAME} MATCHES "KFreeBSD")
+		set(LEVELDB_OS KFREEBSD)
 	elseif(${CMAKE_SYSTEM_NAME} MATCHES "NetBSD")
 		set(LEVELDB_OS NETBSD)
 	elseif(${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
@@ -116,8 +118,7 @@
 		# No idea what's the proper system name is here.
 		set(LEVELDB_OS IOS)
 	else()
-		# Unknown plateform, assume linux.
-		set(LEVELDB_OS LINUX)
+		message(FATAL_ERROR "Cannot build leveldb for ${CMAKE_SYSTEM_NAME}. Please file a bug report.")
 	endif()
 endif()