diff --git a/src/dhcp-common.c b/src/dhcp-common.c
index 08ab9493..9f556557 100644
--- a/src/dhcp-common.c
+++ b/src/dhcp-common.c
@@ -645,14 +645,16 @@ print_option(FILE *fp, const char *prefix, const struct dhcp_opt *opt,
 	if (fputc('=', fp) == EOF)
 		return -1;
 	if (dl == 0)
-		return 1;
+		goto out;
 
 	if (opt->type & OT_RFC1035) {
 		char domain[NS_MAXDNAME];
 
 		sl = decode_rfc1035(domain, sizeof(domain), data, dl);
-		if (sl == 0 || sl == -1)
-			return sl;
+		if (sl == -1)
+			return -1;
+		if (sl == 0)
+			goto out;
 		if (valid_domainname(domain, opt->type) == -1)
 			return -1;
 		return efprintf(fp, "%s", domain);
@@ -693,9 +695,7 @@ print_option(FILE *fp, const char *prefix, const struct dhcp_opt *opt,
 					return -1;
 			}
 		}
-		if (fputc('\0', fp) == EOF)
-			return -1;
-		return 1;
+		goto out;
 	}
 
 	t = data;
@@ -760,6 +760,7 @@ print_option(FILE *fp, const char *prefix, const struct dhcp_opt *opt,
 		}
 	}
 
+out:
 	if (fputc('\0', fp) == EOF)
 		return -1;
 	return 1;
diff --git a/src/script.c b/src/script.c
index 74aef1b1..3dee7b08 100644
--- a/src/script.c
+++ b/src/script.c
@@ -33,6 +33,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
+#include <assert.h>
 #include <ctype.h>
 #include <errno.h>
 #include <signal.h>
@@ -477,12 +478,21 @@ dumplease:
 	fp = NULL;
 #endif
 
+	/* Count the terminated env strings.
+	 * assert that the terminations are correct. */
 	nenv = 0;
 	endp = buf + buf_pos;
 	for (bufp = buf; bufp < endp; bufp++) {
-		if (*bufp == '\0')
+		if (*bufp == '\0') {
+#ifndef NDEBUG
+			if (bufp + 1 < endp)
+				assert(*(bufp + 1) != '\0');
+#endif
 			nenv++;
+		}
 	}
+	assert(*--bufp == '\0');
+
 	if (ctx->script_envlen < nenv) {
 		env = reallocarray(ctx->script_env, nenv + 1, sizeof(*env));
 		if (env == NULL)