binhdrsz = sizeof(struct opt_hdr_v1) +
                        (binarye->binary.nargs + 1) * sizeof(unsigned int) +
                        s.st_size;
-               binhdrsz = ALIGN_SUP(binhdrsz, 32);
+
+               /*
+                * The size includes the binary image size, rounded
+                * up to a 4-byte boundary. Plus 4 bytes for the
+                * next-header byte and 3-byte alignment at the end.
+                */
+               binhdrsz = ALIGN_SUP(binhdrsz, 4) + 4;
                hdr->headersz_lsb = binhdrsz & 0xFFFF;
                hdr->headersz_msb = (binhdrsz & 0xFFFF0000) >> 16;
 
 
                fclose(bin);
 
-               cur += s.st_size;
+               cur += ALIGN_SUP(s.st_size, 4);
 
                /*
                 * For now, we don't support more than one binary
                 * supported. So, the binary header is necessarily the
                 * last one
                 */
-               *((unsigned char *)cur) = 0;
+               *((uint32_t *)cur) = 0x00000000;
 
                cur += sizeof(uint32_t);
        }