diff --git a/include/hardware/keymaster.h b/include/hardware/keymaster.h
index 2c6e29d..40380ad 100644
--- a/include/hardware/keymaster.h
+++ b/include/hardware/keymaster.h
@@ -556,18 +556,6 @@
                                keymaster_operation_handle_t* operation_handle);
 
     /**
-     * Get an estimate of the output that will be generated by calling update() with the specified
-     * number of input bytes, followed by finish().  The estimate may not be exact, but is
-     * guaranteed not to be smaller than sum of the output lengths from update() and finish().  The
-     * estimate takes into account input data already provided.
-     *
-     * \param[in] input_length The number of additional input bytes to be processed.
-     *
-     * \param[out] output_estimate The length of the output that will be produced.
-     */
-    keymaster_error_t (*get_output_size)(size_t input_length, size_t* output_estimate);
-
-    /**
      * Provides data to, and possibly receives output from, an ongoing cryptographic operation begun
      * with begin().
      *