diff --git a/CMakeLists.txt b/CMakeLists.txt
index c720fa1..d929f93 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,8 @@ set(SimpleArchiver_SOURCES
     src/main.c
     src/parser.c
     src/data_structures/linked_list.c
+    src/data_structures/hash_map.c
+    src/algorithms/linear_congruential_gen.c
 )
 
 add_compile_options(
@@ -24,6 +26,8 @@ endif()
 add_executable(simplearchiver ${SimpleArchiver_SOURCES})
 
 add_executable(test_datastructures
-  src/data_structures/test.c
-  src/data_structures/linked_list.c
+    src/data_structures/test.c
+    src/data_structures/linked_list.c
+    src/data_structures/hash_map.c
+    src/algorithms/linear_congruential_gen.c
 )
diff --git a/cosmopolitan/Makefile b/cosmopolitan/Makefile
index d81601f..a9dfc20 100644
--- a/cosmopolitan/Makefile
+++ b/cosmopolitan/Makefile
@@ -6,11 +6,13 @@ OUTDIR = out
 SOURCES = \
 		../src/main.c \
 		../src/parser.c \
-		../src/data_structures/linked_list.c
+		../src/data_structures/linked_list.c \
+		../src/data_structures/hash_map.c
 
 HEADERS = \
 		../src/parser.h \
-		../src/data_structures/linked_list.h
+		../src/data_structures/linked_list.h \
+		../src/data_structures/hash_map.h
 
 OBJECTS = $(addprefix ${OBJDIR}/,$(subst ..,PREVDIR,$(patsubst %.c,%.c.o,${SOURCES})))
 
diff --git a/src/algorithms/linear_congruential_gen.c b/src/algorithms/linear_congruential_gen.c
new file mode 100644
index 0000000..da21c76
--- /dev/null
+++ b/src/algorithms/linear_congruential_gen.c
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2024 Stephen Seo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * `linear_congruential_gen.c` is the source for the linear congruential
+ * generator algorithm.
+ */
+
+#include "linear_congruential_gen.h"
+
+unsigned long long simple_archiver_algo_lcg(unsigned long long seed,
+                                            unsigned long long a,
+                                            unsigned long long c) {
+  // "m" is implicity 2^64.
+  return seed * a + c;
+}
diff --git a/src/algorithms/linear_congruential_gen.h b/src/algorithms/linear_congruential_gen.h
new file mode 100644
index 0000000..a30fe2a
--- /dev/null
+++ b/src/algorithms/linear_congruential_gen.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2024 Stephen Seo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * `linear_congruential_gen.h` is the header for the linear congruential
+ * generator algorithm.
+ */
+
+#ifndef SEODISPARATE_COM_ALGORITHMS_LINEAR_CONGRUENTIAL_GEN_H_
+#define SEODISPARATE_COM_ALGORITHMS_LINEAR_CONGRUENTIAL_GEN_H_
+
+#define SC_ALGO_LCG_DEFAULT_A 0x9ABD
+#define SC_ALGO_LCG_DEFAULT_C 0x2A9A9A9
+
+unsigned long long simple_archiver_algo_lcg(unsigned long long seed,
+                                            unsigned long long a,
+                                            unsigned long long c);
+
+#endif
diff --git a/src/data_structures/hash_map.c b/src/data_structures/hash_map.c
new file mode 100644
index 0000000..56df22a
--- /dev/null
+++ b/src/data_structures/hash_map.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright 2024 Stephen Seo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * `hash_map.c` is the source for a hash map implementation.
+ */
+
+#include "hash_map.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "../algorithms/linear_congruential_gen.h"
+
+typedef struct SDArchiverHashMapData {
+  void *value;
+  void *key;
+  unsigned int key_size;
+  void (*value_cleanup_fn)(void *);
+  void (*key_cleanup_fn)(void *);
+} SDArchiverHashMapData;
+
+typedef struct SDArchiverHashMapKeyData {
+  void *key;
+  unsigned int key_size;
+} SDArchiverHashMapKeyData;
+
+void simple_archiver_hash_map_internal_cleanup_data(void *data) {
+  SDArchiverHashMapData *hash_map_data = data;
+  if (hash_map_data->value) {
+    if (hash_map_data->value_cleanup_fn) {
+      hash_map_data->value_cleanup_fn(hash_map_data->value);
+    } else {
+      free(hash_map_data->value);
+    }
+  }
+
+  if (hash_map_data->key) {
+    if (hash_map_data->key_cleanup_fn) {
+      hash_map_data->key_cleanup_fn(hash_map_data->key);
+    } else {
+      free(hash_map_data->key);
+    }
+  }
+
+  free(data);
+}
+
+int simple_archiver_hash_map_internal_pick_in_list(void *data, void *ud) {
+  SDArchiverHashMapData *hash_map_data = data;
+  SDArchiverHashMapKeyData *key_data = ud;
+
+  return hash_map_data->key_size == key_data->key_size &&
+                 memcmp(hash_map_data->key, key_data->key,
+                        key_data->key_size) == 0
+             ? 1
+             : 0;
+}
+
+unsigned long long simple_archiver_hash_map_internal_key_to_hash(
+    void *key, unsigned int key_size) {
+  unsigned long long seed = 0;
+  unsigned long long temp = 0;
+  unsigned int count = 0;
+  for (unsigned int idx = 0; idx < key_size; ++idx) {
+    temp |= *((unsigned char *)key + count++);
+    if (count >= 8) {
+      count = 0;
+      seed += temp;
+      temp = 0;
+    }
+  }
+  if (temp != 0) {
+    seed += temp;
+  }
+
+  return simple_archiver_algo_lcg(seed, SC_ALGO_LCG_DEFAULT_A,
+                                  SC_ALGO_LCG_DEFAULT_C);
+}
+
+/// Returns 0 on success.
+int simple_archiver_hash_map_internal_rehash(SDArchiverHashMap **hash_map) {
+  if (!hash_map || !*hash_map) {
+    return 1;
+  }
+  SDArchiverHashMap *new_hash_map = malloc(sizeof(SDArchiverHashMap));
+  new_hash_map->buckets_size = (*hash_map)->buckets_size * 2;
+  // Pointers have the same size (at least on the same machine), so
+  // sizeof(void*) should be ok.
+  new_hash_map->buckets = malloc(sizeof(void *) * new_hash_map->buckets_size);
+  for (unsigned int idx = 0; idx < new_hash_map->buckets_size; ++idx) {
+    new_hash_map->buckets[idx] = simple_archiver_list_init();
+  }
+  new_hash_map->count = 0;
+
+  // Iterate through the old hash map to populate the new hash map.
+  for (unsigned int bucket_idx = 0; bucket_idx < (*hash_map)->buckets_size;
+       ++bucket_idx) {
+    SDArchiverLLNode *node = (*hash_map)->buckets[bucket_idx]->head;
+    while (node) {
+      node = node->next;
+      if (node && node != (*hash_map)->buckets[bucket_idx]->tail &&
+          node->data) {
+        SDArchiverHashMapData *data = node->data;
+        simple_archiver_hash_map_insert(&new_hash_map, data->value, data->key,
+                                        data->key_size, data->value_cleanup_fn,
+                                        data->key_cleanup_fn);
+        node->data = NULL;
+      }
+    }
+  }
+
+  simple_archiver_hash_map_free(hash_map);
+  *hash_map = new_hash_map;
+
+  return 0;
+}
+
+SDArchiverHashMap *simple_archiver_hash_map_init(void) {
+  SDArchiverHashMap *hash_map = malloc(sizeof(SDArchiverHashMap));
+  hash_map->buckets_size = SC_SA_DS_HASH_MAP_START_BUCKET_SIZE;
+  // Pointers have the same size (at least on the same machine), so
+  // sizeof(void*) should be ok.
+  hash_map->buckets = malloc(sizeof(void *) * hash_map->buckets_size);
+  for (unsigned int idx = 0; idx < hash_map->buckets_size; ++idx) {
+    hash_map->buckets[idx] = simple_archiver_list_init();
+  }
+  hash_map->count = 0;
+
+  return hash_map;
+}
+
+void simple_archiver_hash_map_free(SDArchiverHashMap **hash_map) {
+  if (hash_map && *hash_map) {
+    for (unsigned int idx = 0; idx < (*hash_map)->buckets_size; ++idx) {
+      SDArchiverLinkedList **linked_list = (*hash_map)->buckets + idx;
+      simple_archiver_list_free(linked_list);
+    }
+
+    free((*hash_map)->buckets);
+    free(*hash_map);
+
+    *hash_map = NULL;
+  }
+}
+
+int simple_archiver_hash_map_insert(SDArchiverHashMap **hash_map, void *value,
+                                    void *key, unsigned int key_size,
+                                    void (*value_cleanup_fn)(void *),
+                                    void (*key_cleanup_fn)(void *)) {
+  if ((*hash_map)->buckets_size <= (*hash_map)->count) {
+    simple_archiver_hash_map_internal_rehash(hash_map);
+  }
+
+  SDArchiverHashMapData *data = malloc(sizeof(SDArchiverHashMapData));
+  data->value = value;
+  data->key = key;
+  data->key_size = key_size;
+  data->value_cleanup_fn = value_cleanup_fn;
+  data->key_cleanup_fn = key_cleanup_fn;
+
+  unsigned long long hash =
+      simple_archiver_hash_map_internal_key_to_hash(key, key_size) %
+      (*hash_map)->buckets_size;
+  int result = simple_archiver_list_add_front(
+      (*hash_map)->buckets[hash], data,
+      simple_archiver_hash_map_internal_cleanup_data);
+
+  if (result == 0) {
+    ++(*hash_map)->count;
+    return 0;
+  } else {
+    if (value) {
+      if (value_cleanup_fn) {
+        value_cleanup_fn(value);
+      } else {
+        free(value);
+      }
+    }
+    if (key) {
+      if (key_cleanup_fn) {
+        key_cleanup_fn(key);
+      } else {
+        free(key);
+      }
+    }
+
+    free(data);
+    return 1;
+  }
+}
+
+void *simple_archiver_hash_map_get(SDArchiverHashMap *hash_map, void *key,
+                                   unsigned int key_size) {
+  unsigned long long hash =
+      simple_archiver_hash_map_internal_key_to_hash(key, key_size) %
+      hash_map->buckets_size;
+
+  SDArchiverLLNode *node = hash_map->buckets[hash]->head;
+  while (node) {
+    node = node->next;
+    if (node && node != hash_map->buckets[hash]->tail && node->data) {
+      SDArchiverHashMapData *data = node->data;
+      if (key_size == data->key_size && memcmp(data->key, key, key_size) == 0) {
+        return data->value;
+      }
+    }
+  }
+
+  return NULL;
+}
+
+int simple_archiver_hash_map_remove(SDArchiverHashMap *hash_map, void *key,
+                                    unsigned int key_size) {
+  unsigned long long hash =
+      simple_archiver_hash_map_internal_key_to_hash(key, key_size) %
+      hash_map->buckets_size;
+
+  SDArchiverHashMapKeyData key_data;
+  key_data.key = key;
+  key_data.key_size = key_size;
+
+  int result = simple_archiver_list_remove(
+      hash_map->buckets[hash], simple_archiver_hash_map_internal_pick_in_list,
+      &key_data);
+  if (result == 1) {
+    return 0;
+  } else if (result > 1) {
+    return 1;
+  } else {
+    return 2;
+  }
+}
diff --git a/src/data_structures/hash_map.h b/src/data_structures/hash_map.h
new file mode 100644
index 0000000..7a61794
--- /dev/null
+++ b/src/data_structures/hash_map.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2024 Stephen Seo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * `hash_map.h` is the header for a hash map implementation.
+ */
+
+#ifndef SEODISPARATE_COM_SIMPLE_ARCHIVER_DATA_STRUCTURE_HASH_MAP_H_
+#define SEODISPARATE_COM_SIMPLE_ARCHIVER_DATA_STRUCTURE_HASH_MAP_H_
+
+#define SC_SA_DS_HASH_MAP_START_BUCKET_SIZE 32
+
+#include "linked_list.h"
+
+typedef struct SDArchiverHashMap {
+  SDArchiverLinkedList **buckets;
+  unsigned int buckets_size;
+  unsigned int count;
+} SDArchiverHashMap;
+
+SDArchiverHashMap *simple_archiver_hash_map_init(void);
+void simple_archiver_hash_map_free(SDArchiverHashMap **hash_map);
+
+/// Returns zero on success.
+/// On failure, frees the value and key using the given functions.
+/// key must remain valid for the lifetime of its entry in the hash map.
+/// If value_cleanup_fn is NULL, then "free" is used instead.
+/// If key_cleanup_fn is NULL, then "free" is used instead.
+int simple_archiver_hash_map_insert(SDArchiverHashMap **hash_map, void *value,
+                                    void *key, unsigned int key_size,
+                                    void (*value_cleanup_fn)(void *),
+                                    void (*key_cleanup_fn)(void *));
+
+/// Returns NULL if not found.
+void *simple_archiver_hash_map_get(SDArchiverHashMap *hash_map, void *key,
+                                   unsigned int key_size);
+
+/// Returns zero on success. Returns one if more than one entry was removed.
+/// Otherwise returns non-zero and non-one value on error.
+int simple_archiver_hash_map_remove(SDArchiverHashMap *hash_map, void *key,
+                                    unsigned int key_size);
+
+#endif
diff --git a/src/data_structures/linked_list.c b/src/data_structures/linked_list.c
index e2af7b4..c4ad0dd 100644
--- a/src/data_structures/linked_list.c
+++ b/src/data_structures/linked_list.c
@@ -84,8 +84,30 @@ int simple_archiver_list_add(SDArchiverLinkedList *list, void *data,
   return 0;
 }
 
+int simple_archiver_list_add_front(SDArchiverLinkedList *list, void *data,
+                                   void (*data_free_fn)(void *)) {
+  if (!list) {
+    return 1;
+  }
+
+  SDArchiverLLNode *new_node = malloc(sizeof(SDArchiverLLNode));
+  new_node->data = data;
+  new_node->data_free_fn = data_free_fn;
+
+  new_node->next = list->head->next;
+  new_node->prev = list->head;
+
+  list->head->next->prev = new_node;
+  list->head->next = new_node;
+
+  ++list->count;
+
+  return 0;
+}
+
 int simple_archiver_list_remove(SDArchiverLinkedList *list,
-                                int (*data_check_fn)(void *)) {
+                                int (*data_check_fn)(void *, void *),
+                                void *user_data) {
   if (!list) {
     return 0;
   }
@@ -100,7 +122,7 @@ int simple_archiver_list_remove(SDArchiverLinkedList *list,
     }
     iter_removed = 0;
     if (node && node != list->tail) {
-      if (data_check_fn(node->data) != 0) {
+      if (data_check_fn(node->data, user_data) != 0) {
         SDArchiverLLNode *temp = node->next;
 
         if (node->data_free_fn) {
@@ -125,7 +147,8 @@ int simple_archiver_list_remove(SDArchiverLinkedList *list,
 }
 
 int simple_archiver_list_remove_once(SDArchiverLinkedList *list,
-                                     int (*data_check_fn)(void *)) {
+                                     int (*data_check_fn)(void *, void *),
+                                     void *user_data) {
   if (!list) {
     return 0;
   }
@@ -134,7 +157,7 @@ int simple_archiver_list_remove_once(SDArchiverLinkedList *list,
   while (node) {
     node = node->next;
     if (node && node != list->tail) {
-      if (data_check_fn(node->data) != 0) {
+      if (data_check_fn(node->data, user_data) != 0) {
         if (node->data_free_fn) {
           node->data_free_fn(node->data);
         } else {
@@ -156,7 +179,8 @@ int simple_archiver_list_remove_once(SDArchiverLinkedList *list,
 }
 
 void *simple_archiver_list_get(SDArchiverLinkedList *list,
-                               int (*data_check_fn)(void *)) {
+                               int (*data_check_fn)(void *, void *),
+                               void *user_data) {
   if (!list) {
     return NULL;
   }
@@ -165,7 +189,7 @@ void *simple_archiver_list_get(SDArchiverLinkedList *list,
   while (node) {
     node = node->next;
     if (node && node != list->tail) {
-      if (data_check_fn(node->data) != 0) {
+      if (data_check_fn(node->data, user_data) != 0) {
         return node->data;
       }
     }
diff --git a/src/data_structures/linked_list.h b/src/data_structures/linked_list.h
index 93609d5..fbebf8e 100644
--- a/src/data_structures/linked_list.h
+++ b/src/data_structures/linked_list.h
@@ -35,26 +35,35 @@ typedef struct SDArchiverLinkedList {
 SDArchiverLinkedList *simple_archiver_list_init(void);
 void simple_archiver_list_free(SDArchiverLinkedList **list);
 
-/// Returns 0 on success.
+/// Returns 0 on success. Puts data at the end of the list
+/// If data_free_fn is NULL, then "free" is used instead.
 int simple_archiver_list_add(SDArchiverLinkedList *list, void *data,
                              void (*data_free_fn)(void *));
 
+/// Returns 0 on success. Puts data at the front of the list
+/// If data_free_fn is NULL, then "free" is used instead.
+int simple_archiver_list_add_front(SDArchiverLinkedList *list, void *data,
+                                   void (*data_free_fn)(void *));
+
 /// Returns number of removed items.
 /// data_check_fn must return non-zero if the data passed to it is to be
 /// removed.
 int simple_archiver_list_remove(SDArchiverLinkedList *list,
-                                int (*data_check_fn)(void *));
+                                int (*data_check_fn)(void *, void *),
+                                void *user_data);
 
 /// Returns 1 on removed, 0 if not removed.
 /// data_check_fn must return non-zero if the data passed to it is to be
 /// removed.
 int simple_archiver_list_remove_once(SDArchiverLinkedList *list,
-                                     int (*data_check_fn)(void *));
+                                     int (*data_check_fn)(void *, void *),
+                                     void *user_data);
 
 /// Returns non-null on success.
 /// data_check_fn must return non-zero if the data passed to it is to be
 /// returned.
 void *simple_archiver_list_get(SDArchiverLinkedList *list,
-                               int (*data_check_fn)(void *));
+                               int (*data_check_fn)(void *, void *),
+                               void *user_data);
 
 #endif
diff --git a/src/data_structures/test.c b/src/data_structures/test.c
index 4121fb7..721232e 100644
--- a/src/data_structures/test.c
+++ b/src/data_structures/test.c
@@ -17,8 +17,10 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
+#include "hash_map.h"
 #include "linked_list.h"
 
 static int checks_checked = 0;
@@ -45,11 +47,17 @@ static int checks_passed = 0;
 
 void no_free_fn(__attribute__((unused)) void *unused) { return; }
 
-int get_one_fn(void *data) { return strcmp(data, "one") == 0 ? 1 : 0; }
+int get_one_fn(void *data, __attribute__((unused)) void *ud) {
+  return strcmp(data, "one") == 0 ? 1 : 0;
+}
 
-int get_two_fn(void *data) { return strcmp(data, "two") == 0 ? 1 : 0; }
+int get_two_fn(void *data, __attribute__((unused)) void *ud) {
+  return strcmp(data, "two") == 0 ? 1 : 0;
+}
 
-int get_three_fn(void *data) { return strcmp(data, "three") == 0 ? 1 : 0; }
+int get_three_fn(void *data, __attribute__((unused)) void *ud) {
+  return strcmp(data, "three") == 0 ? 1 : 0;
+}
 
 int main(void) {
   // Test LinkedList.
@@ -74,28 +82,75 @@ int main(void) {
 
     CHECK_TRUE(list->count == 3);
 
-    void *ptr = simple_archiver_list_get(list, get_one_fn);
+    void *ptr = simple_archiver_list_get(list, get_one_fn, NULL);
     CHECK_TRUE(ptr == one);
 
-    ptr = simple_archiver_list_get(list, get_two_fn);
+    ptr = simple_archiver_list_get(list, get_two_fn, NULL);
     CHECK_TRUE(ptr == two);
 
-    ptr = simple_archiver_list_get(list, get_three_fn);
+    ptr = simple_archiver_list_get(list, get_three_fn, NULL);
     CHECK_TRUE(ptr == three);
 
-    CHECK_TRUE(simple_archiver_list_remove(list, get_two_fn) == 1);
+    CHECK_TRUE(simple_archiver_list_remove(list, get_two_fn, NULL) == 1);
     CHECK_TRUE(list->count == 2);
-    CHECK_TRUE(simple_archiver_list_get(list, get_two_fn) == NULL);
+    CHECK_TRUE(simple_archiver_list_get(list, get_two_fn, NULL) == NULL);
 
-    CHECK_TRUE(simple_archiver_list_remove_once(list, get_one_fn) == 1);
+    CHECK_TRUE(simple_archiver_list_remove_once(list, get_one_fn, NULL) == 1);
     CHECK_TRUE(list->count == 1);
-    CHECK_TRUE(simple_archiver_list_get(list, get_one_fn) == NULL);
+    CHECK_TRUE(simple_archiver_list_get(list, get_one_fn, NULL) == NULL);
 
     simple_archiver_list_free(&list);
 
     CHECK_TRUE(list == NULL);
   }
 
+  // Test HashMap.
+  {
+    SDArchiverHashMap *hash_map = simple_archiver_hash_map_init();
+    simple_archiver_hash_map_free(&hash_map);
+
+    hash_map = simple_archiver_hash_map_init();
+
+    {
+      int *value, *key;
+
+      for (unsigned int idx = 0; idx < 20; ++idx) {
+        value = malloc(sizeof(int));
+        key = malloc(sizeof(int));
+        *value = idx;
+        *key = idx;
+        simple_archiver_hash_map_insert(&hash_map, value, key, sizeof(int),
+                                        NULL, NULL);
+      }
+    }
+
+    int value, key;
+    void *value_ptr;
+
+    for (value = 0, key = 0; value < 20 && key < 20; ++value, ++key) {
+      value_ptr = simple_archiver_hash_map_get(hash_map, &key, sizeof(int));
+      CHECK_TRUE(value_ptr != NULL);
+      CHECK_TRUE(memcmp(value_ptr, &value, sizeof(int)) == 0);
+    }
+
+    key = 5;
+    simple_archiver_hash_map_remove(hash_map, &key, sizeof(int));
+    key = 15;
+    simple_archiver_hash_map_remove(hash_map, &key, sizeof(int));
+
+    for (value = 0, key = 0; value < 20 && key < 20; ++value, ++key) {
+      value_ptr = simple_archiver_hash_map_get(hash_map, &key, sizeof(int));
+      if (key != 5 && key != 15) {
+        CHECK_TRUE(value_ptr != NULL);
+        CHECK_TRUE(memcmp(value_ptr, &value, sizeof(int)) == 0);
+      } else {
+        CHECK_TRUE(value_ptr == NULL);
+      }
+    }
+
+    simple_archiver_hash_map_free(&hash_map);
+  }
+
   printf("Checks checked: %u\n", checks_checked);
   printf("Checks passed:  %u\n", checks_passed);
   return checks_passed == checks_checked ? 0 : 1;