diff --git a/include/ck_bitmap.h b/include/ck_bitmap.h
index 3c0105e..58cc91e 100644
--- a/include/ck_bitmap.h
+++ b/include/ck_bitmap.h
@@ -44,6 +44,7 @@
 #endif
 
 #define CK_BITMAP_BLOCK 	(sizeof(unsigned int) * CHAR_BIT)
+#define CK_BITMAP_OFFSET(i)	((i) % CK_BITMAP_BLOCK)
 #define CK_BITMAP_BIT(i)	(1U << ((i) % CK_BITMAP_BLOCK))
 #define CK_BITMAP_PTR(x, i)	((x) + ((i) / CK_BITMAP_BLOCK))
 #define CK_BITMAP_BLOCKS(n)	(((n) + CK_BITMAP_BLOCK - 1) / CK_BITMAP_BLOCK)
@@ -69,6 +70,9 @@
 #define CK_BITMAP_SET(a, b) \
 	ck_bitmap_set(&(a)->bitmap, (b))
 
+#define CK_BITMAP_BTS(a, b) \
+	ck_bitmap_bts(&(a)->bitmap, (b))
+
 #define CK_BITMAP_RESET(a, b) \
 	ck_bitmap_reset(&(a)->bitmap, (b))
 
@@ -171,6 +175,19 @@ ck_bitmap_set(struct ck_bitmap *bitmap, unsigned int n)
 	return;
 }
 
+/*
+ * Performs a test-and-set operation at the offset specified in the
+ * second argument.
+ * Returns true if the bit at the specified offset was already set,
+ * false otherwise.
+ */
+CK_CC_INLINE static bool
+ck_bitmap_bts(struct ck_bitmap *bitmap, unsigned int n)
+{
+
+	return ck_pr_bts_uint(CK_BITMAP_PTR(bitmap->map, n), CK_BITMAP_OFFSET(n));
+}
+
 /*
  * Resets the bit at the offset specified in the second argument.
  */
diff --git a/regressions/ck_bitmap/validate/serial.c b/regressions/ck_bitmap/validate/serial.c
index 79aca8d..ecc5258 100644
--- a/regressions/ck_bitmap/validate/serial.c
+++ b/regressions/ck_bitmap/validate/serial.c
@@ -73,6 +73,7 @@ check_iteration(ck_bitmap_t *bits, unsigned int len, bool initial)
 static void
 test(ck_bitmap_t *bits, unsigned int n_length, bool initial)
 {
+	bool r;
 	unsigned int i;
 	CK_BITMAP_INSTANCE(8) u;
 
@@ -92,14 +93,35 @@ test(ck_bitmap_t *bits, unsigned int n_length, bool initial)
 		if (ck_bitmap_test(bits, i) == false) {
 			ck_error("[1] ERROR: Expected bit to be set: %u\n", i);
 		}
+
 		ck_bitmap_reset(bits, i);
 		if (ck_bitmap_test(bits, i) == true) {
 			ck_error("[2] ERROR: Expected bit to be cleared: %u\n", i);
 		}
 
+		r = ck_bitmap_bts(bits, i);
+		if (r == true) {
+			ck_error("[3] ERROR: Expected bit to be cleared before 1st bts: %u\n", i);
+		}
+		if (ck_bitmap_test(bits, i) == false) {
+			ck_error("[4] ERROR: Expected bit to be set: %u\n", i);
+		}
+		r = ck_bitmap_bts(bits, i);
+		if (r == false) {
+			ck_error("[5] ERROR: Expected bit to be set before 2nd bts: %u\n", i);
+		}
+		if (ck_bitmap_test(bits, i) == false) {
+			ck_error("[6] ERROR: Expected bit to be set: %u\n", i);
+		}
+
+		ck_bitmap_reset(bits, i);
+		if (ck_bitmap_test(bits, i) == true) {
+			ck_error("[7] ERROR: Expected bit to be cleared: %u\n", i);
+		}
+
 		ck_bitmap_set(bits, i);
 		if (ck_bitmap_test(bits, i) == false) {
-			ck_error("[3] ERROR: Expected bit to be set: %u\n", i);
+			ck_error("[8] ERROR: Expected bit to be set: %u\n", i);
 		}
 
 		check_iteration(bits, i, initial);
@@ -107,7 +129,7 @@ test(ck_bitmap_t *bits, unsigned int n_length, bool initial)
 
 	for (i = 0; i < n_length; i++) {
 		if (ck_bitmap_test(bits, i) == false) {
-			ck_error("[4] ERROR: Expected bit to be set: %u\n", i);
+			ck_error("[9] ERROR: Expected bit to be set: %u\n", i);
 		}
 	}
 
@@ -115,7 +137,7 @@ test(ck_bitmap_t *bits, unsigned int n_length, bool initial)
 
 	for (i = 0; i < n_length; i++) {
 		if (ck_bitmap_test(bits, i) == true) {
-			ck_error("[4] ERROR: Expected bit to be reset: %u\n", i);
+			ck_error("[10] ERROR: Expected bit to be reset: %u\n", i);
 		}
 	}