diff --git a/gmap.py b/gmap.py
index 512a25a..ec0719d 100755
--- a/gmap.py
+++ b/gmap.py
@@ -27,6 +27,7 @@ import re
 import multiprocessing
 import time
 import logging
+import optimizeimages
 
 logging.basicConfig(level=logging.INFO,format="%(asctime)s [%(levelname)s] %(message)s")
 
@@ -103,7 +104,8 @@ def main():
         imgformat = 'png'
 
     if options.optimizeimg:
-        optimizeimg = options.optimizeimg
+        optimizeimg = int(options.optimizeimg)
+        optimizeimages.check_programs(optimizeimg)
     else:
         optimizeimg = None
 
diff --git a/optimizeimages.py b/optimizeimages.py
index 120b60b..7bb35a3 100644
--- a/optimizeimages.py
+++ b/optimizeimages.py
@@ -17,20 +17,33 @@ import os
 import subprocess
 import shlex
 
+pngcrush = "pngcrush"
+optipng = "optipng"
+advdef = "advdef"
+
+def check_programs(level):
+    path = os.environ.get("PATH").split(os.pathsep)
+
+    for prog,l in [(pngcrush,1), (optipng,2), (advdef,2)]:
+        if l <= level:
+            result = filter(lambda x: os.path.exists(os.path.join(x, prog)), path)
+            if len(result) == 0:
+                raise Exception("Optimization prog %s for level %d not found!" % (prog, l))
+
 def optimize_image(imgpath, imgformat, optimizeimg):
     if imgformat == 'png':
-        if optimizeimg == "1" or optimizeimg == "2":
+        if optimizeimg >= 1:
             # we can't do an atomic replace here because windows is terrible
             # so instead, we make temp files, delete the old ones, and rename
             # the temp files. go windows!
-            subprocess.Popen(shlex.split("pngcrush " + imgpath + " " + imgpath + ".tmp"),
+            subprocess.Popen(shlex.split(pngcrush +" " + imgpath + " " + imgpath + ".tmp"),
                 stderr=subprocess.STDOUT, stdout=subprocess.PIPE).communicate()[0]
             os.remove(imgpath)
             os.rename(imgpath+".tmp", imgpath)
 
-        if optimizeimg == "2":
-            subprocess.Popen(shlex.split("optipng " + imgpath), stderr=subprocess.STDOUT,
+        if optimizeimg >= 2:
+            subprocess.Popen(shlex.split(optipng + " " + imgpath), stderr=subprocess.STDOUT,
                 stdout=subprocess.PIPE).communicate()[0]
-            subprocess.Popen(shlex.split("advdef -z4 " + imgpath), stderr=subprocess.STDOUT,
+            subprocess.Popen(shlex.split(advdef + " -z4 " + imgpath), stderr=subprocess.STDOUT,
                 stdout=subprocess.PIPE).communicate()[0]