diff --git a/src/base/SConscript b/src/base/SConscript
index 788aa3e6f..6fc140145 100644
--- a/src/base/SConscript
+++ b/src/base/SConscript
@@ -30,10 +30,26 @@
 
 Import('*')
 
-# base/traceflags.{cc,hh} are generated from base/traceflags.py.
-# $TARGET.base will expand to "<build-dir>/base/traceflags".
-env.Command(['traceflags.hh', 'traceflags.cc'], 'traceflags.py',
-            'python $SOURCE $TARGET.base')
+def make_cc(target, source, env):
+    assert(len(source) == 1)
+    assert(len(target) == 1)
+
+    traceflags = {}
+    execfile(str(source[0]), traceflags)
+    func = traceflags['gen_cc']
+    func(str(target[0]))
+
+def make_hh(target, source, env):
+    assert(len(source) == 1)
+    assert(len(target) == 1)
+
+    traceflags = {}
+    execfile(str(source[0]), traceflags)
+    func = traceflags['gen_hh']
+    func(str(target[0]))
+
+env.Command('traceflags.hh', 'traceflags.py', make_hh)
+env.Command('traceflags.cc', 'traceflags.py', make_cc)
 
 Source('annotate.cc')
 Source('bigint.cc')
diff --git a/src/base/traceflags.py b/src/base/traceflags.py
index e57bfa350..6b241c410 100644
--- a/src/base/traceflags.py
+++ b/src/base/traceflags.py
@@ -350,16 +350,3 @@ const char *Trace::flagStrings[] =
     print >>ccfile, '};'
 
     ccfile.close()
-
-if __name__ == '__main__':
-    # This file generates the header and source files for the flags
-    # that control the tracing facility.
-
-    import sys
-
-    if len(sys.argv) != 2:
-        print "%s: Need argument (basename of cc/hh files)" % sys.argv[0]
-        sys.exit(1)
-
-    gen_hh(sys.argv[1] + '.hh')
-    gen_cc(sys.argv[1] + '.cc')