diff --git a/envi/binary.h b/envi/binary.h
index 0a0477d..3f7216f 100644
--- a/envi/binary.h
+++ b/envi/binary.h
@@ -99,11 +99,17 @@ public:
 		return p;
 	}
 
-	T * saveXY(int x, int y){
+	T * saveXY(unsigned x, unsigned y){
 
 		T * px;
 		unsigned int i;
 
+		if (x<1||x>R[0]||y<1||y>R[1]){                       //make sure the sample and line number is right
+			cout<<"wrong page";
+			getchar();
+			return NULL;
+		}
+
 		px=(T *)malloc(R[2]*sizeof(T));                      //memory allocation
 		if (px==NULL)
 			cout<<"memory allocation failure";	
@@ -116,7 +122,6 @@ public:
 		{
 			file.read((char *)(px+i), sizeof(T));
 			file.seekg((R[1]*R[0]-1)*sizeof(T),ios::cur);    //go to the next band
-			px[i];
 		}
 
 		return px;
--
libgit2 0.21.4