diff -Naur Remmina-08f5b4be5e31a44765d651009be2ac7797fc44ac.old/remmina-plugins/exec/exec_plugin.c Remmina-08f5b4be5e31a44765d651009be2ac7797fc44ac/remmina-plugins/exec/exec_plugin.c
--- Remmina-08f5b4be5e31a44765d651009be2ac7797fc44ac.old/remmina-plugins/exec/exec_plugin.c	2017-12-20 14:08:42.167227579 +0100
+++ Remmina-08f5b4be5e31a44765d651009be2ac7797fc44ac/remmina-plugins/exec/exec_plugin.c	2017-12-20 14:17:09.688627742 +0100
@@ -201,7 +201,7 @@
 			_("WARNING! Executing a command synchronously, may hung Remmina.\r"
 					"Do you really want to continue?");
 		dialog = GTK_DIALOG(gtk_message_dialog_new(NULL, GTK_DIALOG_MODAL,
-					GTK_MESSAGE_QUESTION, GTK_BUTTONS_YES_NO, sync_warning));
+					GTK_MESSAGE_QUESTION, GTK_BUTTONS_YES_NO, "%s", sync_warning));
 		gint result = gtk_dialog_run (GTK_DIALOG (dialog));
 
 		switch (result)