diff --git a/map.c b/map.c
index 3dc2ef4..68d9483 100644
--- a/map.c
+++ b/map.c
@@ -45,7 +45,7 @@ struct hashmap
 
 hashmap* hashmap_create(void)
 {
-	hashmap* m = malloc(sizeof(hashmap));
+	hashmap* m = (hashmap*)malloc(sizeof(hashmap));
 	if (m == NULL)
 	{
 		return NULL;
@@ -58,7 +58,7 @@ hashmap* hashmap_create(void)
 	m->tombstone_count = 0;
 	#endif
 
-	m->buckets = calloc(HASHMAP_DEFAULT_CAPACITY, sizeof(struct bucket));
+	m->buckets = (struct bucket*)calloc(HASHMAP_DEFAULT_CAPACITY, sizeof(struct bucket));
 	m->first = NULL;
 
 	// this prevents branching in hashmap_set.
@@ -98,7 +98,7 @@ static void hashmap_resize(hashmap* m)
 
 	m->capacity *= HASHMAP_RESIZE_FACTOR;
 	// initializes all bucket fields to null
-	m->buckets = calloc(m->capacity, sizeof(struct bucket));
+	m->buckets = (struct bucket*)calloc(m->capacity, sizeof(struct bucket));
 
 	// same trick; avoids branching
 	m->last = (struct bucket*)&m->first;
@@ -222,7 +222,7 @@ void hashmap_set(hashmap* m, const void* key, size_t ksize, uintptr_t val)
 	if (m->count + 1 > HASHMAP_MAX_LOAD * m->capacity)
 		hashmap_resize(m);
 
-	uint32_t hash = hash_data(key, ksize);
+	uint32_t hash = hash_data((const unsigned char*)key, ksize);
 	struct bucket* entry = find_entry(m, key, ksize, hash);
 	if (entry->key == NULL)
 	{
@@ -244,7 +244,7 @@ bool hashmap_get_set(hashmap* m, const void* key, size_t ksize, uintptr_t* out_i
 	if (m->count + 1 > HASHMAP_MAX_LOAD * m->capacity)
 		hashmap_resize(m);
 
-	uint32_t hash = hash_data(key, ksize);
+	uint32_t hash = hash_data((const unsigned char*)key, ksize);
 	struct bucket* entry = find_entry(m, key, ksize, hash);
 	if (entry->key == NULL)
 	{
@@ -270,7 +270,7 @@ void hashmap_set_free(hashmap* m, const void* key, size_t ksize, uintptr_t val,
 	if (m->count + 1 > HASHMAP_MAX_LOAD * m->capacity)
 		hashmap_resize(m);
 
-	uint32_t hash = hash_data(key, ksize);
+	uint32_t hash = hash_data((const unsigned char*)key, ksize);
 	struct bucket *entry = find_entry(m, key, ksize, hash);
 	if (entry->key == NULL)
 	{
@@ -299,7 +299,7 @@ void hashmap_set_free(hashmap* m, const void* key, size_t ksize, uintptr_t val,
 
 bool hashmap_get(hashmap* m, const void* key, size_t ksize, uintptr_t* out_val)
 {
-	uint32_t hash = hash_data(key, ksize);
+	uint32_t hash = hash_data((const unsigned char*)key, ksize);
 	struct bucket* entry = find_entry(m, key, ksize, hash);
 
 	// if there is no match, output val will just be NULL
diff --git a/map.h b/map.h
index 13ac8a9..33d52c4 100644
--- a/map.h
+++ b/map.h
@@ -7,6 +7,10 @@
 #ifndef map_h
 #define map_h
 
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
 #define hashmap_str_lit(str) (str), sizeof(str) - 1
 #define hashmap_static_arr(arr) (arr), sizeof(arr)
 
@@ -72,4 +76,8 @@ void hashmap_iterate(hashmap* map, hashmap_callback c, void* usr);
 // `0` is an empty bucket, `1` is occupied, and `x` is removed.
 //void bucket_dump(hashmap *m);
 
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
 #endif // map_h