diff --git a/examples/memmap.c b/examples/memmap.c
index e1ed73a..8ead360 100644
--- a/examples/memmap.c
+++ b/examples/memmap.c
@@ -1,9 +1,12 @@
 #include <kernaux/memmap.h>
 
 #include <assert.h>
+#include <stdbool.h>
 #include <string.h>
 
-#define SIZE_1GiB (1024 * 1024 * 1024)
+#define SIZE_256MiB ( 256 * 1024 * 1024)
+#define SIZE_512MiB ( 512 * 1024 * 1024)
+#define SIZE_1GiB   (1024 * 1024 * 1024)
 
 KernAux_MemMap memmap;
 
@@ -11,5 +14,9 @@ int main()
 {
     KernAux_MemMap_init(memmap, SIZE_1GiB);
 
+    assert(KernAux_MemMap_add_entry(memmap, true,  NULL,  0,           SIZE_256MiB));
+    assert(KernAux_MemMap_add_entry(memmap, false, "foo", SIZE_256MiB, SIZE_256MiB));
+    assert(KernAux_MemMap_add_entry(memmap, true,  "bar", SIZE_512MiB, SIZE_512MiB));
+
     return 0;
 }
diff --git a/include/kernaux/memmap.h b/include/kernaux/memmap.h
index d75604f..bb1ad8a 100644
--- a/include/kernaux/memmap.h
+++ b/include/kernaux/memmap.h
@@ -28,6 +28,14 @@ typedef struct KernAux_MemMap {
 
 void KernAux_MemMap_init(KernAux_MemMap memmap, size_t memory_size);
 
+bool KernAux_MemMap_add_entry(
+    KernAux_MemMap memmap,
+    bool is_available,
+    const char *tag,
+    size_t start,
+    size_t size
+);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/memmap.c b/src/memmap.c
index fa13d24..f06622c 100644
--- a/src/memmap.c
+++ b/src/memmap.c
@@ -7,6 +7,7 @@
 
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <string.h>
 
 #define MEMMAP (*memmap)
@@ -18,3 +19,41 @@ void KernAux_MemMap_init(KernAux_MemMap memmap, const size_t memory_size)
     MEMMAP.entries_count = 0;
     memset(MEMMAP.entries, 0, sizeof(MEMMAP.entries));
 }
+
+bool KernAux_MemMap_add_entry(
+    KernAux_MemMap memmap,
+    const bool is_available,
+    const char *const tag,
+    const size_t start,
+    const size_t size
+) {
+    if (MEMMAP.is_finished) {
+        KERNAUX_PANIC("memmap is finished");
+        return false;
+    }
+
+    if (MEMMAP.entries_count >= KERNAUX_MEMMAP_ENTRIES_MAX) {
+        KERNAUX_PANIC("memmap is full");
+        return false;
+    }
+
+    if (SIZE_MAX - start < size) {
+        KERNAUX_PANIC("memmap entry limit is too high");
+        return false;
+    }
+
+    memset(MEMMAP.entries[MEMMAP.entries_count], 0, sizeof(MEMMAP.entries[MEMMAP.entries_count]));
+    const size_t index = MEMMAP.entries_count++;
+
+    MEMMAP.entries[index]->is_available = is_available;
+    if (tag) {
+        memset (MEMMAP.entries[index]->tag, 0,   KERNAUX_MEMMAP_ENTRY_TAG_SIZE_MAX);
+        strncpy(MEMMAP.entries[index]->tag, tag, KERNAUX_MEMMAP_ENTRY_TAG_SLEN_MAX);
+    }
+    MEMMAP.entries[index]->start = start;
+    MEMMAP.entries[index]->size  = size;
+    MEMMAP.entries[index]->end   = start + size - 1;
+    MEMMAP.entries[index]->limit = start + size;
+
+    return true;
+}