diff --git a/geometry/grassmann_test.cpp b/geometry/grassmann_test.cpp
index c13d690b14..ab43d9c913 100644
--- a/geometry/grassmann_test.cpp
+++ b/geometry/grassmann_test.cpp
@@ -71,7 +71,7 @@ class GrassmannTest : public testing::Test {
                       Handedness::Right,
                       serialization::Frame::TEST>;
 
-protected:
+ protected:
   R3Element<Length> const null_displacement_ = {0 * Metre,
                                                 0 * Metre,
                                                 0 * Metre};