diff --git a/lib/libfile.c b/lib/libfile.c
index 814cd9c..b42753c 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -36,7 +36,11 @@
 
 	while (size) {
 		now = pwrite(fd, buf, size, offset);
-		if (now <= 0)
+		if (now == 0) {
+			errno = ENOSPC;
+			return -1;
+		}
+		if (now < 0)
 			return now;
 		size -= now;
 		buf += now;
@@ -60,7 +64,11 @@
 
 	while (size) {
 		now = write(fd, buf, size);
-		if (now <= 0)
+		if (now == 0) {
+			errno = ENOSPC;
+			return -1;
+		}
+		if (now < 0)
 			return now;
 		size -= now;
 		buf += now;