diff --git a/src/modules/mavlink/mavlink_parameters.cpp b/src/modules/mavlink/mavlink_parameters.cpp
index 368712e752..01d8a370dd 100644
--- a/src/modules/mavlink/mavlink_parameters.cpp
+++ b/src/modules/mavlink/mavlink_parameters.cpp
@@ -78,7 +78,7 @@ MavlinkParametersManager::handle_message(const mavlink_message_t *msg)
 			if (req_list.target_system == mavlink_system.sysid &&
 			    (req_list.target_component == mavlink_system.compid || req_list.target_component == MAV_COMP_ID_ALL)) {
 
-				_send_all_index = 0;
+				_send_all_index = PARAM_HASH;
 			}
 
 			if (req_list.target_system == mavlink_system.sysid && req_list.target_component < 127 &&
@@ -111,6 +111,17 @@ MavlinkParametersManager::handle_message(const mavlink_message_t *msg)
 				strncpy(name, set.param_id, MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN);
 				/* enforce null termination */
 				name[MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN] = '\0';
+
+				/* Whatever the value is, we're being told to stop sending */
+				if (strncmp(name, "_HASH_CHECK", sizeof(name)) == 0) {
+					char buf[MAVLINK_MSG_STATUSTEXT_FIELD_TEXT_LEN];
+					sprintf(buf, "[pm] hash load stopped param listing");
+					_mavlink->send_statustext_info(buf);
+					_send_all_index = -1;
+					/* No other action taken, return */
+					return;
+				}
+
 				/* attempt to find parameter, set and send it */
 				param_t param = param_find_no_notification(name);
 
@@ -164,6 +175,7 @@ MavlinkParametersManager::handle_message(const mavlink_message_t *msg)
 
 				/* when no index is given, loop through string ids and compare them */
 				if (req_read.param_index < 0) {
+					/* XXX: I left this in so older versions of QGC wouldn't break */
 					if (strncmp(req_read.param_id, HASH_PARAM, MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN) == 0) {
 						/* return hash check for cached params */
 						uint32_t hash = param_hash_check();
@@ -185,7 +197,6 @@ MavlinkParametersManager::handle_message(const mavlink_message_t *msg)
 						/* attempt to find parameter and send it */
 						send_param(param_find_no_notification(name));
 					}
-
 				} else {
 					/* when index is >= 0, send this parameter again */
 					int ret = send_param(param_for_used_index(req_read.param_index));
@@ -301,6 +312,29 @@ MavlinkParametersManager::send(const hrt_abstime t)
 			return;
 		}
 
+		/* The first thing we send is a hash of all values for the ground
+		 * station to try and quickly load a cached copy of our params
+		 */
+		if (_send_all_index == PARAM_HASH) {
+			/* return hash check for cached params */
+			uint32_t hash = param_hash_check();
+
+			/* build the one-off response message */
+			mavlink_param_value_t msg;
+			msg.param_count = param_count_used();
+			msg.param_index = -1;
+			strncpy(msg.param_id, HASH_PARAM, MAVLINK_MSG_PARAM_VALUE_FIELD_PARAM_ID_LEN);
+			msg.param_type = MAV_PARAM_TYPE_UINT32;
+			memcpy(&msg.param_value, &hash, sizeof(hash));
+			_mavlink->send_message(MAVLINK_MSG_ID_PARAM_VALUE, &msg);
+
+			/* after this we should start sending all params */
+			_send_all_index = 0;
+
+			/* No further action, return now */
+			return;
+		}
+
 		/* look for the first parameter which is used */
 		param_t p;
 		do {
@@ -316,7 +350,7 @@ MavlinkParametersManager::send(const hrt_abstime t)
 		if ((p == PARAM_INVALID) || (_send_all_index >= (int) param_count())) {
 			_send_all_index = -1;
 		}
-	} else if (_send_all_index == 0 && hrt_absolute_time() > 20 * 1000 * 1000) {
+	} else if (_send_all_index == PARAM_HASH && hrt_absolute_time() > 20 * 1000 * 1000) {
 		/* the boot did not seem to ever complete, warn user and set boot complete */
 		_mavlink->send_statustext_critical("WARNING: SYSTEM BOOT INCOMPLETE. CHECK CONFIG.");
 		_mavlink->set_boot_complete();
diff --git a/src/modules/systemlib/param/param.c b/src/modules/systemlib/param/param.c
index 1c6518830e..2a8e2c5cfb 100644
--- a/src/modules/systemlib/param/param.c
+++ b/src/modules/systemlib/param/param.c
@@ -1121,7 +1121,7 @@ uint32_t param_hash_check(void)
 		const char *name = param_name(param);
 		const void *val = param_get_value_ptr(param);
 		param_hash = crc32part((const uint8_t *)name, strlen(name), param_hash);
-		param_hash = crc32part(val, sizeof(union param_value_u), param_hash);
+		param_hash = crc32part(val, param_size(param), param_hash);
 	}
 
 	param_unlock();
diff --git a/src/modules/systemlib/param/param.h b/src/modules/systemlib/param/param.h
index 8c49a0b01c..9e2d83d93a 100644
--- a/src/modules/systemlib/param/param.h
+++ b/src/modules/systemlib/param/param.h
@@ -82,6 +82,11 @@ typedef uintptr_t	param_t;
  */
 #define PARAM_INVALID	((uintptr_t)0xffffffff)
 
+/**
+ * Magic handle for hash check param
+ */
+#define PARAM_HASH      ((uintptr_t)INT32_MAX)
+
 /**
  * Look up a parameter by name.
  *