diff --git a/src/libImaging/Imaging.h b/src/libImaging/Imaging.h
index 200a9fe0782..0b23b3b2bce 100644
--- a/src/libImaging/Imaging.h
+++ b/src/libImaging/Imaging.h
@@ -153,26 +153,26 @@ struct ImagingPaletteInstance {
 #define IMAGING_ARENA_UNLOCK(m)
 
 #if defined(__cplusplus)
-    #define IMAGING_ARENA_TLS thread_local
+#define IMAGING_ARENA_TLS thread_local
 #elif defined(HAVE_THREAD_LOCAL)
-    #define IMAGING_ARENA_TLS thread_local
+#define IMAGING_ARENA_TLS thread_local
 #elif defined(HAVE__THREAD_LOCAL)
-    #define IMAGING_ARENA_TLS _Thread_local
+#define IMAGING_ARENA_TLS _Thread_local
 #elif defined(HAVE___THREAD)
-    #define IMAGING_ARENA_TLS __thread
+#define IMAGING_ARENA_TLS __thread
 #elif defined(HAVE___DECLSPEC_THREAD_)
-    #define IMAGING_ARENA_TLS __declspec(thread)
+#define IMAGING_ARENA_TLS __declspec(thread)
 #elif defined(Py_GIL_DISABLED)
-    #define IMAGING_ARENA_TLS
-    #define IMAGING_ARENA_LOCKING
+#define IMAGING_ARENA_TLS
+#define IMAGING_ARENA_LOCKING
 
-    #undef IMAGING_ARENA_LOCK
-    #undef IMAGING_ARENA_UNLOCK
+#undef IMAGING_ARENA_LOCK
+#undef IMAGING_ARENA_UNLOCK
 
-    #define IMAGING_ARENA_LOCK(m) PyMutex_Lock(m)
-    #define IMAGING_ARENA_UNLOCK(m) PyMutex_Unlock(m)
+#define IMAGING_ARENA_LOCK(m) PyMutex_Lock(m)
+#define IMAGING_ARENA_UNLOCK(m) PyMutex_Unlock(m)
 #else
-    #define IMAGING_ARENA_TLS
+#define IMAGING_ARENA_TLS
 #endif
 
 typedef struct ImagingMemoryArena {