diff --git a/bin/sassw b/bin/sassw
index f936346..ca35bff 100755
--- a/bin/sassw
+++ b/bin/sassw
@@ -23,7 +23,20 @@ if os.path.isdir(filename):
 
 def build():
     global sources, directories
-    subprocess.call(['sassc', '-mauto', filename, filename.replace('.scss', '.css')])
+    result = subprocess.run(
+            ['sassc', '-mauto', filename, filename.replace('.scss', '.css')],
+            capture_output=True)
+    sys.stdout.write(result.stdout.decode('utf-8'))
+    sys.stderr.write(result.stderr.decode('utf-8'))
+    if result.returncode:
+        # error
+        with open(filename.replace('.scss', '.css'), 'w') as fd:
+            print('''body::before {
+                      white-space: pre;
+                      font-family: monospace;
+                      content: "%s";
+                     }''' % result.stderr.decode('utf-8').replace('\n', '\\A').replace('"', '\\"'),
+                file=fd)
     basepath = os.path.abspath(os.path.dirname(filename))
     sources = [os.path.abspath(os.path.join(basepath, x)) for x in json.load(open(filename.replace('.scss', '.css.map')))['sources']]
     directories = set([os.path.dirname(x) for x in sources])