diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index a12ff40019..7c720ea672 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -1494,6 +1494,7 @@ save_opt(dig_lookup_t *lookup, char *code, char *value) {
 	if (lookup->ednsopts == NULL) {
 		cloneopts(lookup, NULL);
 	}
+	INSIST(lookup->ednsopts != NULL);
 
 	if (lookup->ednsopts[lookup->ednsoptscnt].value != NULL) {
 		isc_mem_free(mctx, lookup->ednsopts[lookup->ednsoptscnt].value);
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index f90c520540..ba58d02d15 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -445,6 +445,7 @@ more_frags(isc__mem_t *ctx, size_t new_size) {
 	if (ctx->basic_blocks == NULL) {
 		more_basic_blocks(ctx);
 	}
+	INSIST(ctx->basic_blocks != NULL);
 
 	total_size = ctx->mem_target;
 	tmp = ctx->basic_blocks;
@@ -516,6 +517,7 @@ mem_getunlocked(isc__mem_t *ctx, size_t size) {
 	if (ctx->freelists[new_size] == NULL) {
 		more_frags(ctx, new_size);
 	}
+	INSIST(ctx->freelists[new_size] != NULL);
 
 	/*
 	 * The free list uses the "rounded-up" size "new_size".