diff --git a/dibi/drivers/mysql.php b/dibi/drivers/mysql.php
index a536467..66b750c 100644
--- a/dibi/drivers/mysql.php
+++ b/dibi/drivers/mysql.php
@@ -300,9 +300,15 @@ class DibiMySqlDriver extends DibiObject implements IDibiDriver, IDibiResultDriv
 	{
 		switch ($type) {
 		case dibi::TEXT:
+			if (!is_resource($this->connection)) {
+				throw new DibiException('Lost connection to server.');
+			}
 			return "'" . mysql_real_escape_string($value, $this->connection) . "'";
 
 		case dibi::BINARY:
+			if (!is_resource($this->connection)) {
+				throw new DibiException('Lost connection to server.');
+			}
 			return "_binary'" . mysql_real_escape_string($value, $this->connection) . "'";
 
 		case dibi::IDENTIFIER:
diff --git a/dibi/drivers/postgre.php b/dibi/drivers/postgre.php
index e8741e6..a04b466 100644
--- a/dibi/drivers/postgre.php
+++ b/dibi/drivers/postgre.php
@@ -277,6 +277,9 @@ class DibiPostgreDriver extends DibiObject implements IDibiDriver, IDibiResultDr
 		switch ($type) {
 		case dibi::TEXT:
 			if ($this->escMethod) {
+				if (!is_resource($this->connection)) {
+					throw new DibiException('Lost connection to server.');
+				}
 				return "'" . pg_escape_string($this->connection, $value) . "'";
 			} else {
 				return "'" . pg_escape_string($value) . "'";
@@ -284,6 +287,9 @@ class DibiPostgreDriver extends DibiObject implements IDibiDriver, IDibiResultDr
 
 		case dibi::BINARY:
 			if ($this->escMethod) {
+				if (!is_resource($this->connection)) {
+					throw new DibiException('Lost connection to server.');
+				}
 				return "'" . pg_escape_bytea($this->connection, $value) . "'";
 			} else {
 				return "'" . pg_escape_bytea($value) . "'";