diff --git a/Makefile b/Makefile
index 28867f1..878ca5b 100644
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@ venv-clean:
 #+ Compile Python to JavaScript
 build: venv
 	. $(VIRTUAL_ENV_DIR)/bin/activate
-	transcrypt --build --map --nomin -e 6 OOMAnalyser.py
+	transcrypt --build --map --nomin --sform -e 6 OOMAnalyser.py
 	rollup --format=umd --name OOMAnalyser --file=OOMAnalyser.js -- __target__/OOMAnalyser.js
 
 #+ Serve the current directory on http://127.0.0.1:8080
diff --git a/OOMAnalyser.py b/OOMAnalyser.py
index 84b5279..04e1dea 100644
--- a/OOMAnalyser.py
+++ b/OOMAnalyser.py
@@ -651,8 +651,7 @@ class OOMAnalyser(object):
         else:
             flags, unknown = self._hex2flags(self.results['trigger_proc_gfp_mask'], self.kernel_cfg.GFP_FLAGS)
             if unknown:
-                # TODO Missing format specifier {0:x} in Transcrypt?
-                flags.append('0x{}'.format(unknown.toString(16)))
+                flags.append('0x{0:x}'.format(unknown))
             flags = ' | '.join(flags)
 
         self.results['trigger_proc_gfp_mask'] = '{} ({})'.format(self.results['trigger_proc_gfp_mask'], flags)