diff --git a/gtk/gtkflowbox.c b/gtk/gtkflowbox.c
index 26e39c005c..bac2cfa2b7 100644
--- a/gtk/gtkflowbox.c
+++ b/gtk/gtkflowbox.c
@@ -3824,7 +3824,7 @@ gtk_flow_box_class_init (GtkFlowBoxClass *class)
                        P_("Maximum Children Per Line"),
                        P_("The maximum amount of children to request space for "
                           "consecutively in the given orientation."),
-                       0, G_MAXUINT, DEFAULT_MAX_CHILDREN_PER_LINE,
+                       1, G_MAXUINT, DEFAULT_MAX_CHILDREN_PER_LINE,
                        G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
 
   /**
@@ -4621,6 +4621,7 @@ gtk_flow_box_set_max_children_per_line (GtkFlowBox *box,
                                         guint       n_children)
 {
   g_return_if_fail (GTK_IS_FLOW_BOX (box));
+  g_return_if_fail (n_children > 0);
 
   if (BOX_PRIV (box)->max_children_per_line != n_children)
     {