diff --git a/resources.tgz b/resources.tgz
deleted file mode 100644
index 77a51de..0000000
Binary files a/resources.tgz and /dev/null differ
diff --git a/resources/.version b/resources/.version
new file mode 100644
index 0000000..8acdd82
--- /dev/null
+++ b/resources/.version
@@ -0,0 +1 @@
+0.0.1
diff --git a/src/lib/constants.nim b/src/lib/constants.nim
new file mode 100644
index 0000000..1635aa9
--- /dev/null
+++ b/src/lib/constants.nim
@@ -0,0 +1,5 @@
+# vim: set et sta sw=4 ts=4 :
+
+# Don't forget to update resources/.version to match this!
+const VERSION* = "0.0.1"
+
diff --git a/src/lib/embeddedfs.nim b/src/lib/embeddedfs.nim
index 8149b5d..cc8ba80 100644
--- a/src/lib/embeddedfs.nim
+++ b/src/lib/embeddedfs.nim
@@ -9,13 +9,16 @@ import
     std/files,
     std/paths,
     std/strformat,
+    std/strutils,
     std/tempfiles
 
+import
+    constants
+
 type
     EmbeddedFS* = object
     EmbeddedFSError* = object of CatchableError
 
-let embeddedFs* = EmbeddedFS()
 
 when not defined( emscripten ):
     import zippy/tarballs
@@ -33,6 +36,7 @@ else:
     let confFile* = confDir / Path("config.ini")
 
 
+
 proc path*( data: EmbeddedFS, path: string ): Path =
     ## Returns the path of an embedded file.
     return dataDir / Path( path )
@@ -48,23 +52,38 @@ proc `[]`*( data: EmbeddedFS, path: string ): string =
     return f.readAll
 
 
-# TODO: version check, extract over old stuff
-# no-op if versions match
-#
-proc update*( e: EmbeddedFS ) =
-    when not defined( emscripten ):
-        createDir( getDataDir() )
-        createDir( $confDir )
+proc newEmbeddedFS(): EmbeddedFS =
+    ## Initialize the embedded filesystem.
+    ##
+    ## If the current runtime version is different than the binary version,
+    ## re-extract the embedded filesystem to disk.
 
-        # check existing path / version
+    result = EmbeddedFS()
+    when defined( emscripten ): return
 
-        let ( tarball, path ) = createTempFile( "{appname}_resources_".fmt, ".tgz" )
-        tarball.write( RESOURCES )
-        tarball.close
+    try:
+        var fsVersion = readFile( $result.path(".version") )
+        fsVersion.removeSuffix
+        if fsVersion == VERSION: return
+    except:
+        discard
 
-        extractAll( path, $dataDir )
-        removeFile( path )
+    echo "Extracting embedded resources for v{VERSION}".fmt
 
-        let source = dataDir / Path( "config.ini" )
-        if not fileExists( confFile ): moveFile( source, confFile )
+    createDir( getDataDir() )
+    createDir( $confDir )
+
+    let ( tarball, path ) = createTempFile( "{appname}_resources_".fmt, ".tgz" )
+    tarball.write( RESOURCES )
+    tarball.close
+
+    removeDir( $dataDir )
+    extractAll( path, $dataDir )
+    removeFile( path )
+
+    let source = dataDir / Path( "config.ini" )
+    if not fileExists( confFile ): copyFile( $source, $confFile )
+
+
+let embeddedFs* = newEmbeddedFS()
 
diff --git a/src/nim_wasm_test.nim b/src/nim_wasm_test.nim
index 74922e8..772a67b 100644
--- a/src/nim_wasm_test.nim
+++ b/src/nim_wasm_test.nim
@@ -7,6 +7,7 @@ import reasings
 import raylib
 
 import
+    lib/constants,
     lib/configuration,
     lib/embeddedfs