diff --git a/lib/shash.c b/lib/shash.c
index a7b2c6458..2bfc8eb50 100644
--- a/lib/shash.c
+++ b/lib/shash.c
@@ -17,6 +17,7 @@
 #include <config.h>
 #include "openvswitch/shash.h"
 #include "hash.h"
+#include "util.h"
 
 static struct shash_node *shash_find__(const struct shash *,
                                        const char *name, size_t name_len,
@@ -100,6 +101,7 @@ shash_is_empty(const struct shash *shash)
 size_t
 shash_count(const struct shash *shash)
 {
+    ovs_assert(shash);
     return hmap_count(&shash->map);
 }
 
diff --git a/lib/simap.c b/lib/simap.c
index 0ee08d74d..1c01d4ebe 100644
--- a/lib/simap.c
+++ b/lib/simap.c
@@ -17,6 +17,7 @@
 #include <config.h>
 #include "simap.h"
 #include "hash.h"
+#include "util.h"
 
 static size_t hash_name(const char *, size_t length);
 static struct simap_node *simap_find__(const struct simap *,
@@ -84,6 +85,7 @@ simap_is_empty(const struct simap *simap)
 size_t
 simap_count(const struct simap *simap)
 {
+    ovs_assert(simap);
     return hmap_count(&simap->map);
 }
 
diff --git a/lib/smap.c b/lib/smap.c
index 47fb34502..122adca27 100644
--- a/lib/smap.c
+++ b/lib/smap.c
@@ -300,6 +300,7 @@ smap_is_empty(const struct smap *smap)
 size_t
 smap_count(const struct smap *smap)
 {
+    ovs_assert(smap);
     return hmap_count(&smap->map);
 }