diff --git a/course/externallib.php b/course/externallib.php
index c43f1cdf6bb..e24d8c582e3 100644
--- a/course/externallib.php
+++ b/course/externallib.php
@@ -1552,7 +1552,7 @@ class core_course_external extends external_api {
                     }
 
                     if (isset($value)) {
-                        $conditions[$key] = $crit['value'];
+                        $conditions[$key] = $value;
                         $wheres[] = $key . " = :" . $key;
                     }
                 }
diff --git a/course/tests/externallib_test.php b/course/tests/externallib_test.php
index 8ec184b630f..574cb72a1d9 100644
--- a/course/tests/externallib_test.php
+++ b/course/tests/externallib_test.php
@@ -234,6 +234,16 @@ class core_course_externallib_testcase extends externallib_advanced_testcase {
 
         $this->assertEquals(1, count($categories));
 
+        // Same query, but forcing a parameters clean.
+        $categories = core_course_external::get_categories(array(
+            array('key' => 'id', 'value' => "$category1->id"),
+            array('key' => 'idnumber', 'value' => $category1->idnumber),
+            array('key' => 'name', 'value' => $category1->name . "<br/>"),
+            array('key' => 'visible', 'value' => '1')), 0);
+        $categories = external_api::clean_returnvalue(core_course_external::get_categories_returns(), $categories);
+
+        $this->assertEquals(1, count($categories));
+
         // Retrieve categories from parent.
         $categories = core_course_external::get_categories(array(
             array('key' => 'parent', 'value' => $category3->id)), 1);