diff --git a/copyvios/checker.py b/copyvios/checker.py
index dab8526..90c5090 100644
--- a/copyvios/checker.py
+++ b/copyvios/checker.py
@@ -64,8 +64,8 @@ def _get_results(query, follow=True):
         conn = get_db()
         use_engine = 0 if query.use_engine in ("0", "false") else 1
         use_links = 0 if query.use_links in ("0", "false") else 1
-        use_turnitin = 0 if query.turnitin in ("0", "false") else 1
-        if not use_engine and not use_links:
+        use_turnitin = 1 if query.turnitin in ("1", "true") else 0
+        if not use_engine and not use_links and not use_turnitin:
             query.error = "no search method"
             return
 
diff --git a/templates/index.mako b/templates/index.mako
index ba45d69..0add639 100644
--- a/templates/index.mako
+++ b/templates/index.mako
@@ -108,13 +108,13 @@
                         <td id="cv-inner-col2"><label for="action-search">Copyvio&nbsp;search:</label></td>
                         <td id="cv-inner-col3">
                             <input class="cv-search" type="hidden" name="use_engine" value="0" />
-                            <input id="cv-cb-engine" class="cv-search" type="checkbox" name="use_engine" value="1" ${'checked="checked"' if (query.use_engine != "0") else ""} />
+                            <input id="cv-cb-engine" class="cv-search" type="checkbox" name="use_engine" value="1" ${'checked="checked"' if query.use_engine not in ("0", "false") else ""} />
                             <label for="cv-cb-engine">Use&nbsp;search&nbsp;engine</label>
                             <input class="cv-search" type="hidden" name="use_links" value="0" />
-                            <input id="cv-cb-links" class="cv-search" type="checkbox" name="use_links" value="1" ${'checked="checked"' if (query.use_links != "0") else ""} />
+                            <input id="cv-cb-links" class="cv-search" type="checkbox" name="use_links" value="1" ${'checked="checked"' if query.use_links not in ("0", "false") else ""} />
                             <label for="cv-cb-links">Use&nbsp;links&nbsp;in&nbsp;page</label>
                             <input class="cv-search" type="hidden" name="use_links" value="0" />
-                            <span style="white-space:nowrap"><input id="cv-cb-turnitin" class="cv-search" type="checkbox" name="turnitin" value="1" ${'checked="checked"' if (query.turnitin != "0") else ""}/>
+                            <span style="white-space:nowrap"><input id="cv-cb-turnitin" class="cv-search" type="checkbox" name="turnitin" value="1" ${'checked="checked"' if query.turnitin in ("1", "true") else ""}/>
                             <label for="cv-cb-turnitin">Use&nbsp;Turnitin&nbsp;database</label></span>
                         </td>
                     </tr>