diff --git a/nmigen/build/plat.py b/nmigen/build/plat.py
index 2f198a8..7de062a 100644
--- a/nmigen/build/plat.py
+++ b/nmigen/build/plat.py
@@ -236,7 +236,10 @@ class TemplatedPlatform(Platform):
                 # `export VAR=` is treated on Linux.
                 return re.sub(r'^\"\"$', "", os.environ[var_env])
             elif var in kwargs:
-                return textwrap.dedent(kwargs[var]).strip()
+                if isinstance(kwargs[var], str):
+                    return textwrap.dedent(kwargs[var]).strip()
+                else:
+                    return kwargs[var]
             else:
                 return jinja2.Undefined(name=var)