diff --git a/utilization/chat_templates.py b/utilization/chat_templates.py
index abec6411..aba8727b 100644
--- a/utilization/chat_templates.py
+++ b/utilization/chat_templates.py
@@ -5,9 +5,9 @@
 
 def add_space(
     msg: str,
-    auto_leading_space: bool,
-    remove_space_between: bool,
     context: str,
+    auto_leading_space: bool = True,
+    remove_space_between: bool = True,
     starts: Optional[List[str]] = None,
     ends: Optional[List[str]] = None
 ) -> str:
@@ -15,8 +15,8 @@ def add_space(
         context_ends_special = False
         msg_starts_special = False
     else:
-        context_ends_special = any(context.endswith(e) for e in ends)
-        msg_starts_special = any(msg.startswith(s) for s in starts)
+        context_ends_special = any(context.endswith(e) for e in ends if len(e) > 0)
+        msg_starts_special = any(msg.startswith(s) for s in starts if len(s) > 0)
     if (auto_leading_space and msg and context)\
             and not (context[-1].isspace() or msg[0].isspace())\
             and not (context_ends_special and msg_starts_special):
@@ -30,7 +30,14 @@ def smart_space(parts: List[str], auto_leading_space: bool, remove_space_between
     rendered = ""
     for part in parts:
         if part:
-            rendered += add_space(part, auto_leading_space, remove_space_between, rendered, starts, ends)
+            rendered += add_space(
+                part,
+                rendered,
+                auto_leading_space=auto_leading_space,
+                remove_space_between=remove_space_between,
+                starts=starts,
+                ends=ends
+            )
     return rendered
 
 
diff --git a/utilization/model/model_utils/conversation.py b/utilization/model/model_utils/conversation.py
index 55efe4b6..94c34ed0 100644
--- a/utilization/model/model_utils/conversation.py
+++ b/utilization/model/model_utils/conversation.py
@@ -159,7 +159,7 @@ def _get_segs(self, conversations: List["Conversation"], max_turns: int = 1) ->
             for seg in (system, examples, source, target):
                 if len(seg) > 0:
                     if len(result) > 0:
-                        seg = add_space(seg, True, result[-1])
+                        seg = add_space(seg, result[-1])
                     elif self.final_lstrip:
                         seg = seg.lstrip()
                     result += (seg,)
diff --git a/utilization/utils/generation_args.py b/utilization/utils/generation_args.py
index 78493873..3de81a8a 100644
--- a/utilization/utils/generation_args.py
+++ b/utilization/utils/generation_args.py
@@ -98,6 +98,8 @@ def resolve_generation_args(
         # overrides
         if key in extra_generation_args:
             extra = extra_generation_args.pop(key)
+            if value is None and not details.nullable:
+                continue
             if callable(extra):
                 overrided = extra(value, details)
                 for new_key, new_value in overrided.items():