diff --git a/usr.bin/bsdiff/bsdiff/bsdiff.c b/usr.bin/bsdiff/bsdiff/bsdiff.c
index 57243fc50ba0..337e7085b3da 100644
--- a/usr.bin/bsdiff/bsdiff/bsdiff.c
+++ b/usr.bin/bsdiff/bsdiff/bsdiff.c
@@ -212,7 +212,7 @@ int main(int argc,char *argv[])
 
 		for(scsc=scan+=len;scan<newsize;scan++) {
 			len=search(I,old,oldsize,new+scan,newsize-scan,
-					0,oldsize,&pos);
+					0,oldsize-1,&pos);
 
 			for(;scsc<scan+len;scsc++)
 			if((scsc+lastoffset<oldsize) &&