diff --git a/library/constant_time_internal.h b/library/constant_time_internal.h
index 09de92f173..0cb3f2a346 100644
--- a/library/constant_time_internal.h
+++ b/library/constant_time_internal.h
@@ -417,9 +417,11 @@ void mbedtls_ct_memmove_left(void *start,
  *
  * \param condition The condition
  * \param dest      Secret. Destination pointer.
- * \param src1      Secret. Pointer to copy from (if \p condition == MBEDTLS_CT_TRUE). Shouldn't overlap with \p dest.
+ * \param src1      Secret. Pointer to copy from (if \p condition == MBEDTLS_CT_TRUE).
+ *                  This may be equal to \p dest, but may not overlap in other ways.
  * \param src2      Secret (contents only - may branch to test if src2 == NULL).
- *                  Pointer to copy from (if \p condition == MBEDTLS_CT_FALSE and \p src2 is not NULL). Shouldn't overlap with \p dest. May be NULL.
+ *                  Pointer to copy from (if \p condition == MBEDTLS_CT_FALSE and \p src2 is not NULL). May be NULL.
+ *                  This may be equal to \p dest, but may not overlap it in other ways. It may overlap with \p src1.
  * \param len       Number of bytes to copy.
  */
 void mbedtls_ct_memcpy_if(mbedtls_ct_condition_t condition,
@@ -450,7 +452,7 @@ void mbedtls_ct_memcpy_if(mbedtls_ct_condition_t condition,
  *                      buffer of at least \p len bytes.
  * \param src           Secret. The base of the source buffer. This must point to a
  *                      readable buffer of at least \p offset_max + \p len
- *                      bytes. Shouldn't overlap with \p dest.
+ *                      bytes. Shouldn't overlap with \p dest
  * \param offset        Secret. The offset in the source buffer from which to copy.
  *                      This must be no less than \p offset_min and no greater
  *                      than \p offset_max.
diff --git a/tests/suites/test_suite_constant_time.function b/tests/suites/test_suite_constant_time.function
index ac4dd7ab78..2fafa948d6 100644
--- a/tests/suites/test_suite_constant_time.function
+++ b/tests/suites/test_suite_constant_time.function
@@ -224,6 +224,7 @@ void mbedtls_ct_memcpy_if(int eq, int size, int offset)
     ASSERT_ALLOC(result, size + offset);
     ASSERT_ALLOC(expected, size + offset);
 
+    /* Apply offset to result only */
     for (int i = 0; i < size + offset; i++) {
         src[i]      = 1;
         result[i]   = 0xff;
@@ -243,6 +244,8 @@ void mbedtls_ct_memcpy_if(int eq, int size, int offset)
 
     ASSERT_COMPARE(expected, size, result + offset, size);
 
+
+    /* Apply offset to src only */
     for (int i = 0; i < size + offset; i++) {
         src[i]    = 1;
         result[i] = 0xff;
@@ -261,6 +264,8 @@ void mbedtls_ct_memcpy_if(int eq, int size, int offset)
 
     ASSERT_COMPARE(expected, size, result, size);
 
+
+    /* Apply offset to src and src2 */
     for (int i = 0; i < size + offset; i++) {
         src[i]      = 1;
         src2[i]     = 2;
@@ -281,6 +286,25 @@ void mbedtls_ct_memcpy_if(int eq, int size, int offset)
     TEST_CF_PUBLIC(result, size + offset);
 
     ASSERT_COMPARE(expected, size, result, size);
+
+
+    /* result == src == dest */
+    for (int i = 0; i < size + offset; i++) {
+        src[i]      = 2;
+        expected[i] = 2;
+    }
+
+    TEST_CF_SECRET(&secret_eq, sizeof(secret_eq));
+    TEST_CF_SECRET(src, size + offset);
+    TEST_CF_SECRET(result, size + offset);
+
+    mbedtls_ct_memcpy_if(mbedtls_ct_bool(secret_eq), src + offset, src + offset, src + offset, size);
+
+    TEST_CF_PUBLIC(&secret_eq, sizeof(secret_eq));
+    TEST_CF_PUBLIC(src, size + offset);
+    TEST_CF_PUBLIC(result, size + offset);
+
+    ASSERT_COMPARE(expected, size, src + offset, size);
 exit:
     mbedtls_free(src);
     mbedtls_free(src2);