diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 5f9c44c..4cc6442 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -37,7 +37,7 @@
 	mpi_limb_t a;
 	MPI val = NULL;
 
-	while (nbytes >= 0 && buffer[0] == 0) {
+	while (nbytes > 0 && buffer[0] == 0) {
 		buffer++;
 		nbytes--;
 	}