diff --git a/lib/db/cortex.php b/lib/db/cortex.php
index 04b63dd..7b45ead 100644
--- a/lib/db/cortex.php
+++ b/lib/db/cortex.php
@@ -2723,9 +2723,14 @@ public function prepareFilter($cond, $engine, $db, $fieldConf=null, $primary='id
 					list($parts, $args) = $this->convertNamedParams($parts, $args);
 				$ncond = [];
 				foreach ($parts as &$part) {
-					// enhanced IN handling
-					if (is_int(strpos($part, '?'))) {
+					// arg handling
+					$argCount = substr_count($part, '?');
+					if ($argCount > 1) {
+						// function parameters like `foo(?,?,?)`
+						$ncond = array_merge($ncond, array_splice($args, 0, $argCount));
+					} elseif ($argCount === 1) {
 						$val = array_shift($args);
+						// enhanced IN operator args expansion
 						if (is_int($pos = strpos($part, ' IN ?'))) {
 							if ($val instanceof CortexCollection)
 								$val = $val->getAll('_id',TRUE);
@@ -2734,7 +2739,9 @@ public function prepareFilter($cond, $engine, $db, $fieldConf=null, $primary='id
 							$bindMarks = str_repeat('?,',count($val) - 1).'?';
 							$part = substr($part, 0, $pos).' IN ('.$bindMarks.') ';
 							$ncond = array_merge($ncond, $val);
-						} elseif($val === null &&
+						}
+						// comparison against NULL
+						elseif($val === null &&
 							preg_match('/((?:\S[\w\-]+\S.?)+)\s*'.
 								'(!?==?)\s*(?:\?|:\w+)/i',$part,$match)) {
 							$part = ' '.$match[1].' IS '.($match[2][0]=='!'?'NOT ':'').'NULL ';
diff --git a/test/test_common.php b/test/test_common.php
index 00b834d..c1517a4 100644
--- a/test/test_common.php
+++ b/test/test_common.php
@@ -199,7 +199,22 @@ function run()
 				10,20,30,40,50,60),
 			'merge multiple filters');
 
+		$qp = new \DB\CortexQueryParser();
+
+		$test->expect(
+			$qp->prepareFilter(['foo > bar'],'sql', $f3->DB) === ['`foo` > `bar`'],
+			'auto-escape fields'
+		);
+		$test->expect(
+			$qp->prepareFilter(['created_at > DATE_SUB(NOW(), INTERVAL 1 DAY)'],'sql', $f3->DB) === ['`created_at` > DATE_SUB(NOW(), INTERVAL 1 DAY)'],
+			'respect function when auto-escaping'
+		);
+		$test->expect(
+			$qp->prepareFilter(['foo(?,?,3,?)',1,2,4],'sql', $f3->DB) === ['foo(?,?,3,?)',1,2,4],
+			'query parser: correct function args'
+		);
+
 		///////////////////////////////////
 		return $test->results();
 	}
-}
\ No newline at end of file
+}