diff --git a/bit_array.c b/bit_array.c
index 94ba04e..3a0750c 100644
--- a/bit_array.c
+++ b/bit_array.c
@@ -899,6 +899,9 @@ uint64_t bit_array_get_wordn(const BIT_ARRAY* bitarr, bit_index_t start, int n)
 //
 // Set a word at a time
 //
+// Doesn't extend bit array. However it is safe to TRY to set bits beyond the
+// end of the array, as long as: `start` is < `bit_array_length(arr)`
+//
 
 void bit_array_set_word64(BIT_ARRAY* bitarr, bit_index_t start, uint64_t word)
 {
@@ -910,14 +913,14 @@ void bit_array_set_word32(BIT_ARRAY* bitarr, bit_index_t start, uint32_t word)
 {
   assert(start < bitarr->num_of_bits);
   word_t w = _get_word(bitarr, start);
-  _set_word(bitarr, start, (w & ~(word_t)0xffffffff) | word);
+  _set_word(bitarr, start, bitmask_merge(w, word, 0xffffffff00000000UL));
 }
 
 void bit_array_set_word16(BIT_ARRAY* bitarr, bit_index_t start, uint16_t word)
 {
   assert(start < bitarr->num_of_bits);
   word_t w = _get_word(bitarr, start);
-  _set_word(bitarr, start, (w & ~(word_t)0xffff) | word);
+  _set_word(bitarr, start, bitmask_merge(w, word, 0xffffffffffff0000UL));
 }
 
 void bit_array_set_word8(BIT_ARRAY* bitarr, bit_index_t start, uint8_t byte)
diff --git a/bit_array.h b/bit_array.h
index 70b50ad..3b73a63 100644
--- a/bit_array.h
+++ b/bit_array.h
@@ -170,6 +170,8 @@ uint8_t  bit_array_get_word8(const BIT_ARRAY* bitarr, bit_index_t start);
 uint64_t bit_array_get_wordn(const BIT_ARRAY* bitarr, bit_index_t start, int n);
 
 // Set 64 bits at once from a particular start position
+// Doesn't extend bit array. However it is safe to TRY to set bits beyond the
+// end of the array, as long as: `start` is < `bit_array_length(arr)`
 void bit_array_set_word64(BIT_ARRAY* bitarr, bit_index_t start, uint64_t word);
 void bit_array_set_word32(BIT_ARRAY* bitarr, bit_index_t start, uint32_t word);
 void bit_array_set_word16(BIT_ARRAY* bitarr, bit_index_t start, uint16_t word);
diff --git a/dev/bit_array_test.c b/dev/bit_array_test.c
index e209e7c..1d75a95 100644
--- a/dev/bit_array_test.c
+++ b/dev/bit_array_test.c
@@ -2397,6 +2397,39 @@ void test_add_and_minus_single_word()
   SUITE_END();
 }
 
+void test_get_set_bytes()
+{
+  SUITE_START("get/set byte");
+
+  const size_t nbytes = 8;
+  uint8_t bytes[nbytes] = {0x55,0x31,0x5A,0x12,0x02,0x31,0xC3,0x1E};
+  size_t s, i;
+
+  BIT_ARRAY *arr = bit_array_create(nbytes*8);
+
+  // Set bytes using different offsets
+  for(s = 0; s < 8; s++) {
+    bit_array_clear_all(arr);
+    for(i = 0; i < nbytes-1; i++) {
+      bit_array_set_word8(arr, i*8+s, bytes[i]);
+      ASSERT(bit_array_get_word8(arr, i*8+s) == bytes[i]);
+    }
+    // Setting bytes doesn't extend the array - check last byte with masking
+    i = nbytes-1;
+    bit_array_set_word8(arr, i*8+s, bytes[i]);
+    ASSERT(bit_array_get_word8(arr, i*8+s) == (bytes[i] & (0xff>>s)));
+
+    // Check bits
+    for(i = 0; i < s; i++) ASSERT(bit_array_get(arr, i) == 0);
+    for(i = s; i < nbytes*8; i++)
+      ASSERT(bit_array_get(arr, i) == bitset_get(bytes, i-s));
+  }
+
+  bit_array_free(arr);
+
+  SUITE_END();
+}
+
 // test new features of bitarr library.
 //   - resize from 0
 //   - get/set/clear/toggle/assign auto-resize
@@ -2539,6 +2572,7 @@ int main(int argc, char* argv[])
 
   // Test functions
   test_copy();
+  test_get_set_bytes();
 
   test_parity();
   test_interleave();