diff --git a/src/core/org/luaj/vm2/lib/IoLib.java b/src/core/org/luaj/vm2/lib/IoLib.java
index e386f4d8..cf8e1d2e 100644
--- a/src/core/org/luaj/vm2/lib/IoLib.java
+++ b/src/core/org/luaj/vm2/lib/IoLib.java
@@ -546,7 +546,7 @@ public class IoLib extends TwoArgFunction {
 					break item;
 				case LuaValue.TSTRING:
 					fmt = ai.checkstring();
-					if ( fmt.m_length == 2 && fmt.m_bytes[fmt.m_offset] == '*' ) {
+					if ( fmt.m_length >= 2 && fmt.m_bytes[fmt.m_offset] == '*' ) {
 						switch ( fmt.m_bytes[fmt.m_offset+1] ) {
 						case 'n': vi = freadnumber(f); break item;
 						case 'l': vi = freadline(f,false); break item;