diff --git a/prosopopoee b/prosopopoee
index 976eec0..36f70e5 100755
--- a/prosopopoee
+++ b/prosopopoee
@@ -34,6 +34,9 @@ def error(test, error_message):
 
 
 def main():
+    if os.system("which gm > /dev/null") != 0:
+        sys.stderr.write("WARNING: I can't locate the 'gm' binary, I won't be able to resize images.\n")
+
     error(os.path.exists(os.path.join(os.getcwd(), "settings.yaml")), "I can't find a settings.yaml in the current working directory")
 
     settings = yaml.safe_load(open("settings.yaml", "r"))