diff --git a/camlibs/sierra/ChangeLog b/camlibs/sierra/ChangeLog
index 3b3ebcb8c..6ed3749fd 100644
--- a/camlibs/sierra/ChangeLog
+++ b/camlibs/sierra/ChangeLog
@@ -1,3 +1,7 @@
+2002-02-06  Lutz Müller <lutz@users.sourceforge.net>
+
+	* sierra.[c,h]: Lots of additional debugging output.
+
 2002-02-06  Lutz Müller <lutz@users.sourceforge.net>
 
 	* sierra.c (sierra_read_packet_wait): {int res=(res);... 
diff --git a/camlibs/sierra/library.c b/camlibs/sierra/library.c
index 81628f492..c6716f291 100644
--- a/camlibs/sierra/library.c
+++ b/camlibs/sierra/library.c
@@ -138,6 +138,8 @@ int sierra_list_files (Camera *camera, const char *folder, CameraList *list, GPC
 	int count, i, len = 0;
 	char filename[1024];
 
+	GP_DEBUG ("Listing files in folder '%s'...", folder);
+
 	/* We need to change to the folder first */
 	CHECK (sierra_change_folder (camera, folder, context));
 
@@ -583,6 +585,8 @@ sierra_read_packet_wait (Camera *camera, char *buf, GPContext *context)
 		}
 
 		CHECK (result);
+
+		GP_DEBUG ("Packet successfully read.");
 		return (GP_OK);
 	}
 }
@@ -661,13 +665,16 @@ sierra_write_ack (Camera *camera)
 	char buf[4096];
 	int ret;
 
-	GP_DEBUG ("* sierra_write_ack");
+	GP_DEBUG ("Writing acknowledgement...");
 	
 	buf[0] = ACK;
 	ret = sierra_write_packet (camera, buf);
 	if (camera->port->type == GP_PORT_USB && !camera->pl->usb_wrap)
 		gp_port_usb_clear_halt (camera->port, GP_PORT_USB_ENDPOINT_IN);
-	return (ret);
+	CHECK (ret);
+
+	GP_DEBUG ("Successfully wrote acknowledgement.");
+	return (GP_OK);
 }
 
 int sierra_ping (Camera *camera, GPContext *context) 
@@ -821,6 +828,8 @@ int sierra_get_int_register (Camera *camera, int reg, int *value, GPContext *con
 			CHECK (sierra_write_packet (camera, packet));
 
 		CHECK (sierra_read_packet_wait (camera, buf, context));
+		GP_DEBUG ("Successfully read packet. Interpreting result "
+			  "(0x%x)...", buf[0]);
 		switch (buf[0]) {
 		case DC1:
 			gp_context_error (context, _("Could not get "
@@ -833,7 +842,10 @@ int sierra_get_int_register (Camera *camera, int reg, int *value, GPContext *con
 			    ((unsigned char) buf[6] * 65536) +
 			    ((unsigned char) buf[7] * 16777216);
 			*value = r;
+			GP_DEBUG ("Value of register 0x%x: 0x%x. ", reg, r);
 			CHECK (sierra_write_ack (camera));
+			GP_DEBUG ("Read value of register 0x%x and wrote "
+				  "acknowledgement. Returning...", reg);
 			return GP_OK;
 		case ENQ:
 			return GP_OK;
diff --git a/camlibs/sierra/sierra.c b/camlibs/sierra/sierra.c
index d74cfffa6..6deedb7ab 100644
--- a/camlibs/sierra/sierra.c
+++ b/camlibs/sierra/sierra.c
@@ -54,11 +54,41 @@
 #  define N_(String) (String)
 #endif
 
-#define CHECK_STOP(camera,result) {int res; res = result; if (res < 0) {camera_stop (camera, context); gp_log (GP_LOG_DEBUG, "sierra", "Operation failed!"); return (res);}}
+#define CHECK_STOP(camera,result)				\
+{								\
+	int res = (result);					\
+								\
+	if (res < 0) {						\
+		GP_DEBUG ("Operation failed (%i)!", res);	\
+		camera_stop (camera, context);			\
+		return (res);					\
+	}							\
+}
 
-#define CHECK_STOP_FREE(camera,result) {int res; res = result; if (res < 0) {camera_stop (camera, context); free (camera->pl); camera->pl = NULL; return (res);}}
+#define CHECK_STOP_FREE(camera,result)				\
+{								\
+	int res = (result);					\
+								\
+	if (res < 0) {						\
+		GP_DEBUG ("Operation failed (%i)!", res);	\
+		camera_stop (camera, context);			\
+		free (camera->pl);				\
+		camera->pl = NULL;				\
+		return (res);					\
+	}							\
+}
 
-#define CHECK_FREE(camera,result) {int res; res = result; if (res < 0) {free (camera->pl); camera->pl = NULL; return (res);}}
+#define CHECK_FREE(camera,result)				\
+{								\
+	int res = (result);					\
+								\
+	if (res < 0) {						\
+		GP_DEBUG ("Operation failed (%i)!", res);	\
+		free (camera->pl);				\
+		camera->pl = NULL;				\
+		return (res);					\
+	}							\
+}
 
 int camera_start(Camera *camera, GPContext *context);
 int camera_stop(Camera *camera, GPContext *context);
diff --git a/camlibs/sierra/sierra.h b/camlibs/sierra/sierra.h
index 52412815c..57f684aeb 100644
--- a/camlibs/sierra/sierra.h
+++ b/camlibs/sierra/sierra.h
@@ -22,5 +22,14 @@ typedef struct {
 	int  usb_wrap;
 } SierraCamera;
 
-#define CHECK(result) {int res = (result); if (res < 0) return (res);}
+#define CHECK(result)					\
+{							\
+	int res = (result);				\
+							\
+	if (res < 0) {					\
+		gp_log (GP_LOG_DEBUG, "sierra",		\
+			"Operation failed (%i)!", res);	\
+		return (res);				\
+	}						\
+}