diff --git a/source/blender/editors/interface/interface_regions.c b/source/blender/editors/interface/interface_regions.c
index 70716de6bdc..7cce7a0bbed 100644
--- a/source/blender/editors/interface/interface_regions.c
+++ b/source/blender/editors/interface/interface_regions.c
@@ -748,12 +748,14 @@ void ui_searchbox_autocomplete(bContext *C, ARegion *ar, uiBut *but, char *str)
 {
 	uiSearchboxData *data= ar->regiondata;
 
-	data->items.autocpl= autocomplete_begin(str, ui_get_but_string_max_length(but));
+	if(str[0]) {
+		data->items.autocpl= autocomplete_begin(str, ui_get_but_string_max_length(but));
 
-	but->search_func(C, but->search_arg, but->editstr, &data->items);
+		but->search_func(C, but->search_arg, but->editstr, &data->items);
 
-	autocomplete_end(data->items.autocpl, str);
-	data->items.autocpl= NULL;
+		autocomplete_end(data->items.autocpl, str);
+		data->items.autocpl= NULL;
+	}
 }
 
 static void ui_searchbox_region_draw(const bContext *C, ARegion *ar)
diff --git a/source/blender/editors/mesh/editmesh_loop.c b/source/blender/editors/mesh/editmesh_loop.c
index 7fc3753eefb..20fd33fc731 100644
--- a/source/blender/editors/mesh/editmesh_loop.c
+++ b/source/blender/editors/mesh/editmesh_loop.c
@@ -723,7 +723,7 @@ void MESH_OT_knife_cut(wmOperatorType *ot)
 	ot->modal= WM_gesture_lines_modal;
 	ot->exec= knife_cut_exec;
 	
-	ot->poll= ED_operator_editmesh;
+	ot->poll= EM_view3d_poll;
 	
 	/* flags */
 	ot->flag= OPTYPE_REGISTER|OPTYPE_UNDO;
diff --git a/source/blender/editors/space_file/file_ops.c b/source/blender/editors/space_file/file_ops.c
index 65a46d6514d..a217dbe9f57 100644
--- a/source/blender/editors/space_file/file_ops.c
+++ b/source/blender/editors/space_file/file_ops.c
@@ -933,7 +933,7 @@ int file_delete_poll(bContext *C)
 	SpaceFile *sfile= CTX_wm_space_file(C);
 	struct direntry* file;
 
-	if (sfile->params) {
+	if (sfile && sfile->params) {
 		if (sfile->params->active_file < 0) { 
 			poll= 0;
 		} else {