diff --git a/src/Functions/ReplaceRegexpImpl.h b/src/Functions/ReplaceRegexpImpl.h
index bd8d90dcfe4..9f9a6f3bbd0 100644
--- a/src/Functions/ReplaceRegexpImpl.h
+++ b/src/Functions/ReplaceRegexpImpl.h
@@ -243,7 +243,7 @@ struct ReplaceRegexpImpl
 
         for (size_t i = 0; i < input_rows_count; ++i)
         {
-            size_t from = i > 0 ? haystack_offsets[i - 1] : 0;
+            size_t from = haystack_offsets[i - 1];
 
             const char * hs_data = reinterpret_cast<const char *>(haystack_data.data() + from);
             const size_t hs_length = static_cast<unsigned>(haystack_offsets[i] - from - 1);
@@ -274,19 +274,19 @@ struct ReplaceRegexpImpl
 
         for (size_t i = 0; i < input_rows_count; ++i)
         {
-            size_t hs_from = i > 0 ? haystack_offsets[i - 1] : 0;
+            size_t hs_from = haystack_offsets[i - 1];
             const char * hs_data = reinterpret_cast<const char *>(haystack_data.data() + hs_from);
             const size_t hs_length = static_cast<unsigned>(haystack_offsets[i] - hs_from - 1);
 
-            size_t ndl_from = i > 0 ? needle_offsets[i - 1] : 0;
+            size_t ndl_from = needle_offsets[i - 1];
             const char * ndl_data = reinterpret_cast<const char *>(needle_data.data() + ndl_from);
             const size_t ndl_length = static_cast<unsigned>(needle_offsets[i] - ndl_from - 1);
             std::string_view needle(ndl_data, ndl_length);
 
             if (needle.empty())
             {
-                memcpySmallAllowReadWriteOverflow15(&res_data[i > 0 ? res_offsets[i - 1] : 0], hs_data, hs_length + 1);
-                res_offsets[i] = (i > 0 ? res_offsets[i - 1] : 0) + hs_length + 1;
+                res_data.insert(res_data.end(), hs_data, hs_data + hs_length);
+                res_offsets[i] = res_offsets[i - 1] + hs_length + 1;
                 continue;
             }
 
@@ -336,11 +336,11 @@ struct ReplaceRegexpImpl
 
         for (size_t i = 0; i < input_rows_count; ++i)
         {
-            size_t hs_from = i > 0 ? haystack_offsets[i - 1] : 0;
+            size_t hs_from = haystack_offsets[i - 1];
             const char * hs_data = reinterpret_cast<const char *>(haystack_data.data() + hs_from);
             const size_t hs_length = static_cast<unsigned>(haystack_offsets[i] - hs_from - 1);
 
-            size_t repl_from = i > 0 ? replacement_offsets[i - 1] : 0;
+            size_t repl_from = replacement_offsets[i - 1];
             const char * repl_data = reinterpret_cast<const char *>(replacement_data.data() + repl_from);
             const size_t repl_length = static_cast<unsigned>(replacement_offsets[i] - repl_from - 1);
             std::string_view replacement(repl_data, repl_length);
@@ -375,23 +375,23 @@ struct ReplaceRegexpImpl
 
         for (size_t i = 0; i < input_rows_count; ++i)
         {
-            size_t hs_from = i > 0 ? haystack_offsets[i - 1] : 0;
+            size_t hs_from = haystack_offsets[i - 1];
             const char * hs_data = reinterpret_cast<const char *>(haystack_data.data() + hs_from);
             const size_t hs_length = static_cast<unsigned>(haystack_offsets[i] - hs_from - 1);
 
-            size_t ndl_from = i > 0 ? needle_offsets[i - 1] : 0;
+            size_t ndl_from = needle_offsets[i - 1];
             const char * ndl_data = reinterpret_cast<const char *>(needle_data.data() + ndl_from);
             const size_t ndl_length = static_cast<unsigned>(needle_offsets[i] - ndl_from - 1);
             std::string_view needle(ndl_data, ndl_length);
 
             if (needle.empty())
             {
-                memcpySmallAllowReadWriteOverflow15(&res_data[i > 0 ? res_offsets[i - 1] : 0], hs_data, hs_length + 1);
-                res_offsets[i] = (i > 0 ? res_offsets[i - 1] : 0) + hs_length + 1;
+                res_data.insert(res_data.end(), hs_data, hs_data + hs_length);
+                res_offsets[i] = res_offsets[i - 1] + hs_length + 1;
                 continue;
             }
 
-            size_t repl_from = i > 0 ? replacement_offsets[i - 1] : 0;
+            size_t repl_from = replacement_offsets[i - 1];
             const char * repl_data = reinterpret_cast<const char *>(replacement_data.data() + repl_from);
             const size_t repl_length = static_cast<unsigned>(replacement_offsets[i] - repl_from - 1);
             std::string_view replacement(repl_data, repl_length);