diff --git a/src/grc/grc.c b/src/grc/grc.c
index e48bffbff..084849883 100644
--- a/src/grc/grc.c
+++ b/src/grc/grc.c
@@ -96,8 +96,13 @@ int blocks,rest;
 			if (bytes==0)
 				AbEnd("couldn't read %s:%s\n",argv[i],strerror(errno));
 			blocks = bytes / 254;
-			rest = bytes % 254 + 1;
-			if (rest>255) rest=255;
+			rest = bytes % 254;
+			if (rest==0) {
+			    rest = 255;
+			    --blocks;
+			} else {
+			    ++rest;
+			}
 			vlirtabt[j]=blocks+1; vlirtabs[j]=rest;
 			fwrite(buffer,1,(blocks+1)*254,outCVT);
 		}