1 files changed, 3 insertions, 2 deletions
diff --git a/src/cmd/core/cat.c b/src/cmd/core/cat.c
index aeed1be..92b082d 100644
--- a/src/cmd/core/cat.c
+++ b/src/cmd/core/cat.c
@@ -11,15 +11,16 @@ usage(void)
 static void
 cat(int fd, char *s)
 {
+    int err;
     intptr nr, nw;
     char buf[8192];
 
-    while(!(sys·read(fd, buf, sizeof(buf), &nr))){
+    while(!(err=sys·read(fd, buf, sizeof(buf), &nr)) && nr>0){
         if(sys·write(1, buf, nr, &nw) || nr != nw)
             fmt·panic("write error copying %s: %r", s);
     }
 
-    if(nr<0)
+    if(err)
         fmt·panic("error reading %s: %r", s);
 }