diff --git a/src/include/options.h b/src/include/options.h
index 75062bf..bf8f27e 100644
--- a/src/include/options.h
+++ b/src/include/options.h
@@ -30,7 +30,8 @@ typedef enum {
 	PV_ACTION_NOTHING,		/* do nothing, and exit */
 	PV_ACTION_TRANSFER,		/* transfer data */
 	PV_ACTION_STORE_AND_FORWARD,	/* store to file, then output from it */
-	PV_ACTION_WATCHFD		/* watch process file descriptors */
+	PV_ACTION_WATCHFD,		/* watch process file descriptors */
+	PV_ACTION_QUERY			/* watch the state of another pv */
 } pvaction_t;
 
 /*
diff --git a/src/main/main.c b/src/main/main.c
index 6b6c8f8..437ea85 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -26,6 +26,8 @@
 int pv_remote_set(opts_t, pvstate_t);
 void pv_remote_init(void);
 void pv_remote_fini(void);
+// TODO
+// int pv_remote_transferstate_fetch(pvstate_t, pid_t, /*@null@ */ off_t *);
 
 /*
  * Write a PID file, returning nonzero on error.  Write it atomically, such
@@ -368,8 +370,6 @@ int main(int argc, char **argv)
 		}
 	}
 
-	/* TODO: add logic for --query mode. */
-
 	/*
 	 * If no files were given, pretend "-" was given (stdin).
 	 */
@@ -492,6 +492,31 @@ int main(int argc, char **argv)
 		}
 	}
 
+	/* Initialise the signal handling. */
+	pv_sig_init(state);
+
+	/*
+	 * Get the total size, in query mode.
+	 *
+	 * Note that this uses signals, so signal handling has to have been
+	 * set up first.
+	 */
+	if (PV_ACTION_QUERY == opts->action) {
+		opts->size = 0;
+// TODO         retcode = pv_remote_transferstate_fetch(state, opts->query, &(opts->size));
+		if (0 != retcode) {
+			pv_sig_fini(state);
+			pv_state_free(state);
+			opts_free(opts);
+			return retcode;
+		}
+		/* As above - no ETA if the size is unknown. */
+		if (opts->size < 1) {
+			can_have_eta = false;
+			debug("%s", "size unknown - ETA disabled");
+		}
+	}
+
 	/*
 	 * Copy the remaining parameters from the options into the main
 	 * state.
@@ -534,9 +559,6 @@ int main(int argc, char **argv)
 	debug("%s: %s", "terminal_supports_utf8", terminal_supports_utf8 ? "true" : "false");
 	pv_state_set_terminal_supports_utf8(state, terminal_supports_utf8);
 
-	/* Initialise the signal handling. */
-	pv_sig_init(state);
-
 	/* Run the appropriate main loop. */
 	switch (opts->action) {
 	case PV_ACTION_NOTHING:
@@ -557,6 +579,12 @@ int main(int argc, char **argv)
 		/* "Watch file descriptor(s) of another process" mode. */
 		retcode = pv_watchfd_loop(state);
 		break;
+	case PV_ACTION_QUERY:
+		/* "Watch progress of another pv" mode. */
+		pv_remote_init();
+		/* TODO: loop watching transfer progress until finished. */
+		pv_remote_fini();
+		break;
 	}
 
 	/* Clear up the PID file, if one was written. */
diff --git a/src/main/options.c b/src/main/options.c
index 4d1c199..3b24719 100644
--- a/src/main/options.c
+++ b/src/main/options.c
@@ -999,6 +999,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 			break;
 		case 'Q':
 			opts->query = (pid_t) pv_getnum_count(optarg, false);
+			opts->action = PV_ACTION_QUERY;
 			break;
 		case 'P':
 			opts->pidfile = pv_strdup(optarg);