diff --git a/text_extensions_for_pandas/array/span.py b/text_extensions_for_pandas/array/span.py
index 585c94b9..577393e4 100644
--- a/text_extensions_for_pandas/array/span.py
+++ b/text_extensions_for_pandas/array/span.py
@@ -466,6 +466,17 @@ def __hash__(self):
                                self._ends.tobytes()))
         return self._hash
 
+    def __contains__(self, item) -> bool:
+        """
+        Return true if scalar item exists in this SpanArray.
+        :param item: scalar Span value.
+        :return: true if item exists in this SpanArray.
+        """
+        if isinstance(item, Span) and \
+                item.begin == Span.NULL_OFFSET_VALUE:
+            return Span.NULL_OFFSET_VALUE in self._begins
+        return super().__contains__(item)
+
     def equals(self, other: "SpanArray"):
         """
         :param other: A second `SpanArray`
@@ -541,12 +552,16 @@ def _from_sequence(cls, scalars, dtype=None, copy=False):
         i = 0
         for s in scalars:
             if not isinstance(s, Span):
-                raise ValueError(f"Can only convert a sequence of Span "
-                                 f"objects to a SpanArray. Found an "
-                                 f"object of type {type(s)}")
-            if text is None:
+                # TODO: Temporary fix for np.nan values, pandas-dev GH#38980
+                if np.isnan(s):
+                    s = Span(text, Span.NULL_OFFSET_VALUE, Span.NULL_OFFSET_VALUE)
+                else:
+                    raise ValueError(f"Can only convert a sequence of Span "
+                                     f"objects to a SpanArray. Found an "
+                                     f"object of type {type(s)}")
+            if text is None and s.begin != Span.NULL_OFFSET_VALUE:
                 text = s.target_text
-            if s.target_text != text:
+            if s.target_text != text and s.begin != Span.NULL_OFFSET_VALUE:
                 raise ValueError(
                     f"Mixing different target texts is not currently "
                     f"supported. Received two different strings:\n"
diff --git a/text_extensions_for_pandas/array/tensor.py b/text_extensions_for_pandas/array/tensor.py
index 380fbc88..3929e557 100644
--- a/text_extensions_for_pandas/array/tensor.py
+++ b/text_extensions_for_pandas/array/tensor.py
@@ -433,7 +433,7 @@ def __setitem__(self, key: Union[int, np.ndarray], value: Any) -> None:
     def __contains__(self, item) -> bool:
         if isinstance(item, TensorElement):
             npitem = np.asarray(item)
-            if npitem.size == 1 and  np.isnan(npitem).all():
+            if npitem.size == 1 and np.isnan(npitem).all():
                 return self.isna().any()
         return super().__contains__(item)
 
diff --git a/text_extensions_for_pandas/array/token_span.py b/text_extensions_for_pandas/array/token_span.py
index 2ab04474..ef6da686 100644
--- a/text_extensions_for_pandas/array/token_span.py
+++ b/text_extensions_for_pandas/array/token_span.py
@@ -433,6 +433,17 @@ def __hash__(self):
             self._hash = SpanArray.__hash__(self)
         return self._hash
 
+    def __contains__(self, item) -> bool:
+        """
+        Return true if scalar item exists in this TokenSpanArray.
+        :param item: scalar TokenSpan value.
+        :return: true if item exists in this TokenSpanArray.
+        """
+        if isinstance(item, TokenSpan) and \
+                item.begin == TokenSpan.NULL_OFFSET_VALUE:
+            return TokenSpan.NULL_OFFSET_VALUE in self._begin_tokens
+        return super().__contains__(item)
+
     @classmethod
     def _concat_same_type(
         cls, to_concat: Sequence[pd.api.extensions.ExtensionArray]
@@ -474,7 +485,7 @@ def _from_sequence(cls, scalars, dtype=None, copy=False):
         for information about this method.
         """
         tokens = None
-        if isinstance(scalars, Span):
+        if isinstance(scalars, TokenSpan):
             scalars = [scalars]
         if isinstance(scalars, TokenSpanArray):
             tokens = scalars.tokens
@@ -483,14 +494,18 @@ def _from_sequence(cls, scalars, dtype=None, copy=False):
         i = 0
         for s in scalars:
             if not isinstance(s, TokenSpan):
-                raise ValueError(
-                    f"Can only convert a sequence of TokenSpan "
-                    f"objects to a TokenSpanArray. Found an "
-                    f"object of type {type(s)}"
-                )
-            if tokens is None:
+                # TODO: Temporary fix for np.nan values, pandas-dev GH#38980
+                if np.isnan(s):
+                    s = TokenSpanDtype().na_value
+                else:
+                    raise ValueError(
+                        f"Can only convert a sequence of TokenSpan "
+                        f"objects to a TokenSpanArray. Found an "
+                        f"object of type {type(s)}"
+                    )
+            if tokens is None and not (s.begin == TokenSpan.NULL_OFFSET_VALUE and s.tokens.target_text is None):
                 tokens = s.tokens
-            if not s.tokens.equals(tokens):
+            if not (s.begin == TokenSpan.NULL_OFFSET_VALUE and s.tokens.target_text is None) and not s.tokens.equals(tokens):
                 raise ValueError(
                     f"Mixing different token sets is not currently "
                     f"supported. Received two token sets:\n"