diff --git a/GCDWebDAVServer/GCDWebDAVServer.h b/GCDWebDAVServer/GCDWebDAVServer.h
index 8dee89f..007829b 100644
--- a/GCDWebDAVServer/GCDWebDAVServer.h
+++ b/GCDWebDAVServer/GCDWebDAVServer.h
@@ -47,6 +47,7 @@
 - (instancetype)initWithUploadDirectory:(NSString*)path;
 @end
 
+// These methods can be called from any thread
 @interface GCDWebDAVServer (Subclassing)
 - (BOOL)shouldUploadFileAtPath:(NSString*)path withTemporaryFile:(NSString*)tempPath;  // Default implementation returns YES
 - (BOOL)shouldMoveItemFromPath:(NSString*)fromPath toPath:(NSString*)toPath;  // Default implementation returns YES
diff --git a/GCDWebServer/Core/GCDWebServerConnection.h b/GCDWebServer/Core/GCDWebServerConnection.h
index 7e6cbae..ad88be0 100644
--- a/GCDWebServer/Core/GCDWebServerConnection.h
+++ b/GCDWebServer/Core/GCDWebServerConnection.h
@@ -39,6 +39,7 @@
 @property(nonatomic, readonly) NSUInteger totalBytesWritten;
 @end
 
+// These methods can be called from any thread
 @interface GCDWebServerConnection (Subclassing)
 - (BOOL)open;  // Return NO to reject connection e.g. after validating local or remote addresses
 - (void)didReadBytes:(const void*)bytes length:(NSUInteger)length;  // Called after data has been read from the connection
diff --git a/GCDWebUploader/GCDWebUploader.h b/GCDWebUploader/GCDWebUploader.h
index 109ecc5..30b18c3 100644
--- a/GCDWebUploader/GCDWebUploader.h
+++ b/GCDWebUploader/GCDWebUploader.h
@@ -51,6 +51,7 @@
 - (instancetype)initWithUploadDirectory:(NSString*)path;
 @end
 
+// These methods can be called from any thread
 @interface GCDWebUploader (Subclassing)
 - (BOOL)shouldUploadFileAtPath:(NSString*)path withTemporaryFile:(NSString*)tempPath;  // Default implementation returns YES
 - (BOOL)shouldMoveItemFromPath:(NSString*)fromPath toPath:(NSString*)toPath;  // Default implementation returns YES