diff --git a/src/flake8/processor.py b/src/flake8/processor.py
index fdc47c6..6b7d3c4 100644
--- a/src/flake8/processor.py
+++ b/src/flake8/processor.py
@@ -92,8 +92,8 @@ class FileProcessor:
         self.indent_level = 0
         #: Number of spaces used for indentation
         self.indent_size = options.indent_size
-        #: String representing the space indentation
-        self.indent_size_str = self.indent_size * " "
+        #: String representing the space indentation (DEPRECATED)
+        self.indent_size_str = str(self.indent_size)
         #: Line number in the file
         self.line_number = 0
         #: Current logical line