diff --git a/core/database.class.php b/core/database.class.php
index 6e8a0213..bd97af19 100644
--- a/core/database.class.php
+++ b/core/database.class.php
@@ -56,7 +56,7 @@ class DBEngine {
 	}
 
 	public function create_table_sql($name, $data) {
-		return "CREATE TABLE $name ($data)";
+		return 'CREATE TABLE '.$name.' ('.$data.')';
 	}
 }
 class MySQL extends DBEngine {
@@ -82,7 +82,7 @@ class MySQL extends DBEngine {
 	public function create_table_sql($name, $data) {
 		$data = $this->scoreql_to_sql($data);
 		$ctes = "ENGINE=InnoDB DEFAULT CHARSET='utf8'";
-		return "CREATE TABLE $name ($data) $ctes";
+		return 'CREATE TABLE '.$name.' ('.$data.') '.$ctes;
 	}
 }
 class PostgreSQL extends DBEngine {
@@ -103,7 +103,7 @@ class PostgreSQL extends DBEngine {
 
 	public function create_table_sql($name, $data) {
 		$data = $this->scoreql_to_sql($data);
-		return "CREATE TABLE $name ($data)";
+		return 'CREATE TABLE '.$name.' ('.$data.')';
 	}
 }
 
@@ -151,14 +151,14 @@ class SQLite extends DBEngine {
 			$matches = array();
 			if(preg_match("/INDEX\s*\((.*)\)/", $bit, $matches)) {
 				$col = $matches[1];
-				$extras .= "CREATE INDEX {$name}_{$col} on $name($col);";
+				$extras .= 'CREATE INDEX '.$name.'_'.$col.' on '.$name($col).';';
 			}
 			else {
 				$cols[] = $bit;
 			}
 		}
 		$cols_redone = implode(", ", $cols);
-		return "CREATE TABLE $name ($cols_redone); $extras";
+		return 'CREATE TABLE '.$name.' ('.$cols_redone.'); '.$extras;
 	}
 }
 // }}}
@@ -331,10 +331,10 @@ class Database {
 			if (!array_key_exists(0, $args)) {
 				foreach($args as $name=>$value) {
 					if(is_numeric($value)) {
-						$stmt->bindValue(":$name", $value, PDO::PARAM_INT);
+						$stmt->bindValue(':'.$name, $value, PDO::PARAM_INT);
 					}
 					else {
-						$stmt->bindValue(":$name", $value, PDO::PARAM_STR);
+						$stmt->bindValue(':'.$name, $value, PDO::PARAM_STR);
 					}
 				}
 				$stmt->execute();
diff --git a/core/event.class.php b/core/event.class.php
index 14043de4..69a93175 100644
--- a/core/event.class.php
+++ b/core/event.class.php
@@ -68,7 +68,7 @@ class PageRequestEvent extends Event {
 	}
 
 	public function count_args() {
-		return $this->arg_count - $this->part_count;
+		return (int)($this->arg_count - $this->part_count);
 	}
 
 	/*
@@ -76,20 +76,20 @@ class PageRequestEvent extends Event {
 	 */
 	public function get_search_terms() {
 		$search_terms = array();
-		if($this->count_args() == 2) {
+		if($this->count_args() === 2) {
 			$search_terms = explode(' ', $this->get_arg(0));
 		}
 		return $search_terms;
 	}
 	public function get_page_number() {
 		$page_number = 1;
-		if($this->count_args() == 1) {
+		if($this->count_args() === 1) {
 			$page_number = int_escape($this->get_arg(0));
 		}
-		else if($this->count_args() == 2) {
+		else if($this->count_args() === 2) {
 			$page_number = int_escape($this->get_arg(1));
 		}
-		if($page_number == 0) $page_number = 1; // invalid -> 0
+		if($page_number === 0) $page_number = 1; // invalid -> 0
 		return $page_number;
 	}
 	public function get_page_size() {
diff --git a/core/imageboard.pack.php b/core/imageboard.pack.php
index d07a571b..81ac9674 100644
--- a/core/imageboard.pack.php
+++ b/core/imageboard.pack.php
@@ -514,7 +514,7 @@ class Image {
 	private static function build_search_querylet($terms) {
 		assert(is_array($terms));
 		global $database;
-		if($database->engine->name == "mysql")
+		if($database->engine->name === "mysql")
 			return Image::build_ugly_search_querylet($terms);
 		else
 			return Image::build_accurate_search_querylet($terms);
@@ -750,11 +750,13 @@ class Image {
 		foreach($tag_querylets as $tq) {
 			global $tag_n;
 			$sign = $tq->positive ? "+" : "-";
-			$sql .= " $sign (tag LIKE :tag$tag_n)";
-			$terms["tag$tag_n"] = $tq->tag;
+			//$sql .= " $sign (tag LIKE :tag$tag_n)";
+			$sql .= ' '.$sign.' (tag LIKE :tag'.$tag_n.')';
+			//$terms["tag$tag_n"] = $tq->tag;
+			$terms['tag'.$tag_n] = $tq->tag;
 			$tag_n++;
 			
-			if($sign == "+") $positive_tag_count++;
+			if($sign === "+") $positive_tag_count++;
 			else $negative_tag_count++;
 		}
 		$tag_search = new Querylet($sql, $terms);
@@ -783,7 +785,7 @@ class Image {
 		}
 
 		// one positive tag (a common case), do an optimised search
-		else if($positive_tag_count == 1 && $negative_tag_count == 0) {
+		else if($positive_tag_count === 1 && $negative_tag_count === 0) {
 			$query = new Querylet(
 				// MySQL is braindead, and does a full table scan on images, running the subquery once for each row -_-
 				// "{$this->get_images} WHERE images.id IN (SELECT image_id FROM tags WHERE tag LIKE ?) ",
@@ -819,22 +821,22 @@ class Image {
 			if($tags_ok) {
 				$tag_id_list = join(', ', $tag_id_array);
 
-				$subquery = new Querylet("
-					SELECT images.*, SUM({$tag_search->sql}) AS score
+				$subquery = new Querylet('
+					SELECT images.*, SUM('.$tag_search->sql.') AS score
 					FROM images
 					LEFT JOIN image_tags ON image_tags.image_id = images.id
 					JOIN tags ON image_tags.tag_id = tags.id
-					WHERE tags.id IN ({$tag_id_list})
+					WHERE tags.id IN ('.$tag_id_list.')
 					GROUP BY images.id
-					HAVING score = :score",
+					HAVING score = :score',
 					array_merge(
 						$tag_search->variables,
 						array("score"=>$positive_tag_count)
 					)
 				);
-				$query = new Querylet("
+				$query = new Querylet('
 					SELECT *, UNIX_TIMESTAMP(posted) AS posted_timestamp
-					FROM ({$subquery->sql}) AS images ", $subquery->variables);
+					FROM ('.$subquery->sql.') AS images ', $subquery->variables);
 
 				if(strlen($img_search->sql) > 0) {
 					$query->append_sql(" WHERE ");
@@ -882,9 +884,9 @@ class Tag {
 		if(is_string($tags)) {
 			$tags = explode(' ', $tags);
 		}
-		else if(is_array($tags)) {
+		//else if(is_array($tags)) {
 			// do nothing
-		}
+		//}
 
 		$tags = array_map("trim", $tags);
 
@@ -907,13 +909,13 @@ class Tag {
 	public static function implode($tags) {
 		assert(is_string($tags) || is_array($tags));
 
-		if(is_string($tags)) {
-			// do nothing
-		}
-		else if(is_array($tags)) {
+		if(is_array($tags)) {
 			sort($tags);
 			$tags = implode(' ', $tags);
 		}
+		//else if(is_string($tags)) {
+			// do nothing
+		//}
 
 		return $tags;
 	}
diff --git a/core/page.class.php b/core/page.class.php
index d382caf2..398fb10d 100644
--- a/core/page.class.php
+++ b/core/page.class.php
@@ -242,22 +242,22 @@ class Page {
 			// caching failed, add all files to html_headers.
 			
 			foreach(glob("lib/*.css") as $css) {
-				$this->add_html_header("<link rel='stylesheet' href='$data_href/$css' type='text/css'>");
+				$this->add_html_header('<link rel="stylesheet" href="'.$data_href.'/'.$css.'" type="text/css">');
 			}
 			$css_files = glob("ext/*/style.css");
 			if($css_files) {
 				foreach($css_files as $css_file) {
-					$this->add_html_header("<link rel='stylesheet' href='$data_href/$css_file' type='text/css'>");
+					$this->add_html_header('<link rel="stylesheet" href="'.$data_href.'/'.$css_file.'" type="text/css">');
 				}
 			}
 			
 			foreach(glob("lib/*.js") as $js) {
-				$this->add_html_header("<script src='$data_href/$js' type='text/javascript'></script>");
+				$this->add_html_header('<script src="'.$data_href.'/'.$js'" type="text/javascript"></script>');
 			}
 			$js_files = glob("ext/*/script.js");
 			if($js_files) {
 				foreach($js_files as $js_file) {
-					$this->add_html_header("<script src='$data_href/$js_file' type='text/javascript'></script>");
+					$this->add_html_header('<script src="'.$data_href.'/'.$js_file'" type="text/javascript"></script>');
 				}
 			}
 		}
@@ -362,12 +362,12 @@ class Page {
 		} else {
 			// Caching of CSS disabled.
 			foreach(glob("lib/*.css") as $css) {
-				$this->add_html_header("<link rel='stylesheet' href='$data_href/$css' type='text/css'>");
+				$this->add_html_header('<link rel="stylesheet" href="'.$data_href.'/'.$css.'" type="text/css">');
 			}
 			$css_files = glob("ext/*/style.css");
 			if($css_files) {
 				foreach($css_files as $css_file) {
-					$this->add_html_header("<link rel='stylesheet' href='$data_href/$css_file' type='text/css'>");
+					$this->add_html_header('<link rel="stylesheet" href="'.$data_href.'/'.$css_file.'" type="text/css">');
 				}
 			}	
 		}
@@ -412,12 +412,12 @@ class Page {
 		} else {
 			// Caching of Javascript disabled.
 			foreach(glob("lib/*.js") as $js) {
-				$this->add_html_header("<script src='$data_href/$js' type='text/javascript'></script>");
+				$this->add_html_header('<script src="'.$data_href.'/'.$js'" type="text/javascript"></script>');
 			}
 			$js_files = glob("ext/*/script.js");
 			if($js_files) {
 				foreach($js_files as $js_file) {
-					$this->add_html_header("<script src='$data_href/$js_file' type='text/javascript'></script>");
+					$this->add_html_header('<script src="'.$data_href.'/'.$js_file'" type="text/javascript"></script>');
 				}
 			}
 		}
diff --git a/core/user.class.php b/core/user.class.php
index 7352122b..b5779020 100644
--- a/core/user.class.php
+++ b/core/user.class.php
@@ -40,7 +40,7 @@ class User {
 
 	public static function by_session($name, $session) {
 		global $config, $database;
-		if($database->engine->name == "mysql") {
+		if($database->engine->name === "mysql") {
 			$query = "SELECT * FROM users WHERE name = :name AND md5(concat(pass, :ip)) = :sess";
 		}
 		else {
@@ -53,12 +53,12 @@ class User {
 	public static function by_id($id) {
 		assert(is_numeric($id));
 		global $database;
-		if($id == 1) {
-			$cached = $database->cache->get("user-id:$id");
+		if($id === 1) {
+			$cached = $database->cache->get('user-id:'.$id);
 			if($cached) return new User($cached);
 		}
 		$row = $database->get_row("SELECT * FROM users WHERE id = :id", array("id"=>$id));
-		if($id == 1) $database->cache->set("user-id:$id", $row, 300);
+		if($id === 1) $database->cache->set('user-id:'.$id, $row, 300);
 		return is_null($row) ? null : new User($row);
 	}
 
@@ -148,7 +148,7 @@ class User {
 	public function get_avatar_html() {
 		// FIXME: configurable
 		global $config;
-		if($config->get_string("avatar_host") == "gravatar") {
+		if($config->get_string("avatar_host") === "gravatar") {
 			if(!empty($this->email)) {
 				$hash = md5(strtolower($this->email));
 				$s = $config->get_string("avatar_gravatar_size");
@@ -180,7 +180,7 @@ class User {
 
 	public function get_auth_html() {
 		$at = $this->get_auth_token();
-		return "<input type='hidden' name='auth_token' value='$at'>";
+		return '<input type="hidden" name="auth_token" value="'.$at.'">';
 	}
 
 	public function check_auth_token() {