diff --git a/libfprint/drivers_api.h b/libfprint/drivers_api.h
index f65defd..7edc397 100644
--- a/libfprint/drivers_api.h
+++ b/libfprint/drivers_api.h
@@ -139,9 +139,5 @@ void fpi_imgdev_image_captured(struct fp_img_dev *imgdev, struct fp_img *img);
 void fpi_imgdev_abort_scan(struct fp_img_dev *imgdev, int result);
 void fpi_imgdev_session_error(struct fp_img_dev *imgdev, int error);
 
-/* utils */
-int fpi_std_sq_dev(const unsigned char *buf, int size);
-int fpi_mean_sq_diff_norm(unsigned char *buf1, unsigned char *buf2, int size);
-
 #endif
 
diff --git a/libfprint/fpi-img.h b/libfprint/fpi-img.h
index 87709ff..616db3f 100644
--- a/libfprint/fpi-img.h
+++ b/libfprint/fpi-img.h
@@ -1,5 +1,4 @@
 /*
- * Driver API definitions
  * Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
  * Copyright (C) 2018 Bastien Nocera <hadess@hadess.net>
  *
@@ -48,4 +47,7 @@ struct fp_img *fpi_img_new_for_imgdev(struct fp_img_dev *dev);
 struct fp_img *fpi_img_resize(struct fp_img *img, size_t newsize);
 struct fp_img *fpi_im_resize(struct fp_img *img, unsigned int w_factor, unsigned int h_factor);
 
+int fpi_std_sq_dev(const unsigned char *buf, int size);
+int fpi_mean_sq_diff_norm(unsigned char *buf1, unsigned char *buf2, int size);
+
 #endif