diff --git a/bin/ophis b/bin/ophis
index c368123..f293e4e 100755
--- a/bin/ophis
+++ b/bin/ophis
@@ -1,10 +1,10 @@
 #!/usr/bin/env python
 
 from os.path import realpath, dirname, join
-from sys import argv, path
+from sys import argv, exit, path
 
 path.insert(0, join(dirname(realpath(argv[0])), '..', 'src'))
 
 import Ophis.Main
 
-Ophis.Main.run_ophis(argv[1:])
+exit(Ophis.Main.run_ophis(argv[1:]))
diff --git a/src/Ophis/Macro.py b/src/Ophis/Macro.py
index 65b0017..ffd2337 100644
--- a/src/Ophis/Macro.py
+++ b/src/Ophis/Macro.py
@@ -11,7 +11,6 @@
 import sys
 
 import Ophis.IR as IR
-import Ophis.CmdLine as Cmd
 import Ophis.Errors as Err
 
 macros = {}
diff --git a/src/Ophis/Main.py b/src/Ophis/Main.py
index 5f93bf4..feedc00 100644
--- a/src/Ophis/Main.py
+++ b/src/Ophis/Main.py
@@ -20,7 +20,12 @@ import Ophis.Opcodes
 
 
 def run_all():
-    "Transforms the source infiles to a binary outfile."
+    """Transforms the source infiles to a binary outfile.
+
+    Returns a shell-style exit code: 1 if there were errors, 0 if there
+    were no errors.
+
+    """
     Err.count = 0
     z = Ophis.Frontend.parse(Ophis.CmdLine.infiles)
     env = Ophis.Environment.Environment()
@@ -69,7 +74,7 @@ def run_all():
             if outfile == '-':
                 output = sys.stdout
                 if sys.platform == "win32":
-                    # We can't dump our binary in test mode; that would be
+                    # We can't dump our binary in text mode; that would be
                     # disastrous. So, we'll do some platform-specific
                     # things here to force our stdout to binary mode.
                     import msvcrt
@@ -82,10 +87,13 @@ def run_all():
             output.flush()
             if outfile != '-':
                 output.close()
+            return 0
         except IOError:
             print>>sys.stderr, "Could not write to " + outfile
+            return 1
     else:
         Err.report()
+        return 1
 
 
 def run_ophis(args):
@@ -98,8 +106,8 @@ def run_ophis(args):
         Ophis.Opcodes.opcodes.update(Ophis.Opcodes.c02extensions)
 
     Ophis.CorePragmas.reset()
-    run_all()
+    return run_all()
 
 
 if __name__ == '__main__':
-    run_ophis(sys.argv[1:])
+    sys.exit(run_ophis(sys.argv[1:]))
diff --git a/src/tools/opcodes/gensets.py b/src/tools/opcodes/gensets.py
index 84a5991..10ebac7 100755
--- a/src/tools/opcodes/gensets.py
+++ b/src/tools/opcodes/gensets.py
@@ -142,7 +142,7 @@ def dump_map(m, prologue=''):
 
 if __name__ == '__main__':
     if len(sys.argv) > 1:
-        chipsets = argv[1:]
+        chipsets = sys.argv[1:]
     else:
         chipsets = ['chipsets.txt']
     archs = []