diff --git wp-includes/wp-db.php wp-includes/wp-db.php
index 5393240..403f945 100644
--- wp-includes/wp-db.php
+++ wp-includes/wp-db.php
@@ -1202,7 +1202,7 @@ class wpdb {
 			return;
 
 		// This is not meant to be foolproof -- but it will catch obviously incorrect usage.
-		if ( strpos( $query, '%' ) === false ) {
+		if ( strpos( $query, '%' ) === false && strpos( $query, ':' ) === false ) {
 			_doing_it_wrong( 'wpdb::prepare', sprintf( __( 'The query argument of %s must have a placeholder.' ), 'wpdb::prepare()' ), '3.9' );
 		}
 
@@ -1211,11 +1211,28 @@ class wpdb {
 		// If args were passed as an array (as in vsprintf), move them up
 		if ( isset( $args[0] ) && is_array($args[0]) )
 			$args = $args[0];
+
+		array_walk( $args, array( $this, 'escape_by_ref' ) );
+
+		// If args were passed as associative array then they're named params
+		if ( array_values($args) !== $args ) {
+			foreach ( $args as $key => $value ) {
+				// Make sure all $keys have ':' preceding them
+				$new_key = ':' . ltrim( $key, ':' );
+				unset( $args[$key] );
+				$args[ $new_key ] = $value;
+				// In case someone mistakenly already singlequoted/doublequoted it
+				$query = str_replace( array( "'$new_key'", '"' . $new_key . '"') , $new_key, $query );
+			}
+			return strtr( $query, $args );
+		}
+
+		// Else it's in traditional vsprintf format
 		$query = str_replace( "'%s'", '%s', $query ); // in case someone mistakenly already singlequoted it
 		$query = str_replace( '"%s"', '%s', $query ); // doublequote unquoting
 		$query = preg_replace( '|(?<!%)%f|' , '%F', $query ); // Force floats to be locale unaware
 		$query = preg_replace( '|(?<!%)%s|', "'%s'", $query ); // quote the strings, avoiding escaped strings like %%s
-		array_walk( $args, array( $this, 'escape_by_ref' ) );
+
 		return @vsprintf( $query, $args );
 	}