diff --git a/app/sdks/MyCaptcha.class.php b/app/sdks/MyCaptcha.class.php
index 3833230..9f5f5dc 100755
--- a/app/sdks/MyCaptcha.class.php
+++ b/app/sdks/MyCaptcha.class.php
@@ -30,12 +30,12 @@ class MyCaptcha{
 			for($i=0;$i<$fontfile_width && $symbol<$alphabet_length;$i++){
 				$transparent = (imagecolorat($font, $i, 0) >> 24) == 127;
 				if(!$reading_symbol && !$transparent){
-					$font_metrics[$alphabet{$symbol}]=array('start'=>$i);
+					$font_metrics[$alphabet[$symbol]]=array('start'=>$i);
 					$reading_symbol=true;
 					continue;
 				}
 				if($reading_symbol && $transparent){
-					$font_metrics[$alphabet{$symbol}]['end']=$i;
+					$font_metrics[$alphabet[$symbol]]['end']=$i;
 					$reading_symbol=false;
 					$symbol++;
 					continue;
@@ -51,7 +51,7 @@ class MyCaptcha{
 			$odd=mt_rand(0,1);
 			if($odd==0) $odd=-1;
 			for($i=0;$i<$length;$i++){
-				$m=$font_metrics[$this->keystring{$i}];
+				$m=$font_metrics[$this->keystring[$i]];
 
 				$y=(($i%2)*$fluctuation_amplitude - $fluctuation_amplitude/2)*$odd
 					+ mt_rand(-round($fluctuation_amplitude/3), round($fluctuation_amplitude/3))
@@ -149,7 +149,7 @@ class MyCaptcha{
 		while(true){
 			$str = '';
 			for($i=0;$i<$length;$i++){
-				$str .= $allowed_symbols{mt_rand(0,strlen($allowed_symbols)-1)};
+				$str .= $allowed_symbols[mt_rand(0,strlen($allowed_symbols)-1)];
 			}
 			if(!preg_match('/cp|cb|ck|c6|c9|rn|rm|mm|co|do|cl|db|qp|qb|dp|ww/',$str)) break;
 		}