diff --git a/include/binaryfusefilter.h b/include/binaryfusefilter.h
index 14dbf4e..05d0a2c 100644
--- a/include/binaryfusefilter.h
+++ b/include/binaryfusefilter.h
@@ -279,6 +279,10 @@ static inline uint8_t binary_fuse_mod3(uint8_t x) {
 // many duplicated keys.
 static inline bool binary_fuse8_populate(uint64_t *keys, uint32_t size,
                            binary_fuse8_t *filter) {
+  if (size != filter->Size) {
+    return false;
+  }
+
   uint64_t rng_counter = 0x726b2b9d438b9d4d;
   filter->Seed = binary_fuse_rng_splitmix64(&rng_counter);
   uint64_t *reverseOrder = (uint64_t *)calloc((size + 1), sizeof(uint64_t));
@@ -569,6 +573,10 @@ static inline void binary_fuse16_free(binary_fuse16_t *filter) {
 // many duplicated keys.
 static inline bool binary_fuse16_populate(uint64_t *keys, uint32_t size,
                            binary_fuse16_t *filter) {
+  if (size != filter->Size) {
+    return false;
+  }
+
   uint64_t rng_counter = 0x726b2b9d438b9d4d;
   filter->Seed = binary_fuse_rng_splitmix64(&rng_counter);
   uint64_t *reverseOrder = (uint64_t *)calloc((size + 1), sizeof(uint64_t));
@@ -747,14 +755,14 @@ static inline bool binary_fuse16_populate(uint64_t *keys, uint32_t size,
 }
 
 static inline size_t binary_fuse16_serialization_bytes(binary_fuse16_t *filter) {
-  return sizeof(filter->Seed) + sizeof(filter->SegmentLength) +
+  return sizeof(filter->Seed) + sizeof(filter->Size) + sizeof(filter->SegmentLength) +
         sizeof(filter->SegmentLengthMask) + sizeof(filter->SegmentCount) +
         sizeof(filter->SegmentCountLength) + sizeof(filter->ArrayLength) +
         sizeof(uint16_t) * filter->ArrayLength;
 }
 
 static inline size_t binary_fuse8_serialization_bytes(const binary_fuse8_t *filter) {
-  return sizeof(filter->Seed) + sizeof(filter->SegmentLength) +
+  return sizeof(filter->Seed) + sizeof(filter->Size) + sizeof(filter->SegmentLength) +
    sizeof(filter->SegmentCount) +
         sizeof(filter->SegmentCountLength) + sizeof(filter->ArrayLength) +
         sizeof(uint8_t) * filter->ArrayLength;
@@ -766,6 +774,8 @@ static inline size_t binary_fuse8_serialization_bytes(const binary_fuse8_t *filt
 static inline void binary_fuse16_serialize(const binary_fuse16_t *filter, char *buffer) {
   memcpy(buffer, &filter->Seed, sizeof(filter->Seed));
   buffer += sizeof(filter->Seed);
+  memcpy(buffer, &filter->Size, sizeof(filter->Size));
+  buffer += sizeof(filter->Size);
   memcpy(buffer, &filter->SegmentLength, sizeof(filter->SegmentLength));
   buffer += sizeof(filter->SegmentLength);
   memcpy(buffer, &filter->SegmentCount, sizeof(filter->SegmentCount));
@@ -783,6 +793,8 @@ static inline void binary_fuse16_serialize(const binary_fuse16_t *filter, char *
 static inline void binary_fuse8_serialize(const binary_fuse8_t *filter, char *buffer) {
   memcpy(buffer, &filter->Seed, sizeof(filter->Seed));
   buffer += sizeof(filter->Seed);
+  memcpy(buffer, &filter->Size, sizeof(filter->Size));
+  buffer += sizeof(filter->Size);
   memcpy(buffer, &filter->SegmentLength, sizeof(filter->SegmentLength));
   buffer += sizeof(filter->SegmentLength);
   memcpy(buffer, &filter->SegmentCount, sizeof(filter->SegmentCount));
@@ -802,6 +814,8 @@ static inline void binary_fuse8_serialize(const binary_fuse8_t *filter, char *bu
 static inline const char* binary_fuse16_deserialize_header(binary_fuse16_t* filter, const char* buffer) {
   memcpy(&filter->Seed, buffer, sizeof(filter->Seed));
   buffer += sizeof(filter->Seed);
+  memcpy(&filter->Size, buffer, sizeof(filter->Size));
+  buffer += sizeof(filter->Size);
   memcpy(&filter->SegmentLength, buffer, sizeof(filter->SegmentLength));
   buffer += sizeof(filter->SegmentLength);
   filter->SegmentLengthMask = filter->SegmentLength - 1;
@@ -837,6 +851,8 @@ static inline bool binary_fuse16_deserialize(binary_fuse16_t * filter, const cha
 static inline const char* binary_fuse8_deserialize_header(binary_fuse8_t* filter, const char* buffer) {
   memcpy(&filter->Seed, buffer, sizeof(filter->Seed));
   buffer += sizeof(filter->Seed);
+  memcpy(&filter->Size, buffer, sizeof(filter->Size));
+  buffer += sizeof(filter->Size);
   memcpy(&filter->SegmentLength, buffer, sizeof(filter->SegmentLength));
   buffer += sizeof(filter->SegmentLength);
   filter->SegmentLengthMask = filter->SegmentLength - 1;
diff --git a/tests/unit.c b/tests/unit.c
index cd7ad0c..abe5725 100644
--- a/tests/unit.c
+++ b/tests/unit.c
@@ -191,6 +191,35 @@ bool testbufferedxor16(size_t size) {
 bool testbinaryfuse8(size_t size, size_t repeated_size) {
   printf("testing binary fuse8 with size %zu and %zu duplicates\n", size, repeated_size);
   binary_fuse8_t filter;
+
+  // size serialization test
+  binary_fuse8_allocate((uint32_t)size, &filter);
+  uint64_t *big_set = (uint64_t *)malloc(sizeof(uint64_t) * size);
+  for (size_t i = 0; i < size; i++) {
+    big_set[i] = i;
+  }
+  if (!binary_fuse8_populate(big_set, (uint32_t)size, &filter)) {
+    return false;
+  }
+  free(big_set);
+
+  size_t buffer_size = binary_fuse8_serialization_bytes(&filter);
+  char *buffer = (char *)malloc(buffer_size);
+  binary_fuse8_serialize(&filter, buffer);
+  binary_fuse8_free(&filter);
+  binary_fuse8_deserialize(&filter, buffer);
+
+  if (filter.Size != size) {
+    printf("size not (de-)serialized correctly, found %d, expected %zu.",
+           filter.Size, size);
+    free(buffer);
+    binary_fuse8_free(&filter);
+    return false;
+  }
+  free(buffer);
+  binary_fuse8_free(&filter);
+  // end of size serialization test
+
   return test(size, repeated_size, &filter,
               binary_fuse8_allocate_gen,
               binary_fuse8_free_gen,
@@ -205,6 +234,36 @@ bool testbinaryfuse8(size_t size, size_t repeated_size) {
 bool testbinaryfuse16(size_t size, size_t repeated_size) {
   printf("testing binary fuse16 with size %zu and %zu duplicates\n", size, repeated_size);
   binary_fuse16_t filter;
+
+  // size serialization test
+  binary_fuse16_allocate((uint32_t)size, &filter);
+  uint64_t *big_set = (uint64_t *)malloc(sizeof(uint64_t) * size);
+  for (size_t i = 0; i < size; i++) {
+    big_set[i] = i;
+  }
+  if (!binary_fuse16_populate(big_set, (uint32_t)size, &filter)) {
+    return false;
+  }
+  free(big_set);
+
+  size_t buffer_size = binary_fuse16_serialization_bytes(&filter);
+  char *buffer = (char *)malloc(buffer_size);
+  binary_fuse16_serialize(&filter, buffer);
+  binary_fuse16_free(&filter);
+  binary_fuse16_deserialize(&filter, buffer);
+
+  if (filter.Size != size) {
+    printf("size not (de-)serialized correctly, found %d, expected %zu.",
+           filter.Size, size);
+    free(buffer);
+    binary_fuse16_free(&filter);
+    return false;
+  }
+
+  free(buffer);
+  binary_fuse16_free(&filter);
+  // end of size serialization test
+
   return test(size, repeated_size, &filter,
               binary_fuse16_allocate_gen,
               binary_fuse16_free_gen,