diff --git a/README.md b/README.md
index f85e14b..e875180 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,7 @@
 
 [![bitformat](https://raw.githubusercontent.com/scott-griffiths/bitformat/main/doc/bitformat_logo_small.png)](https://github.com/scott-griffiths/bitformat)
 
+[![PyPI - Version](https://img.shields.io/pypi/v/bitformat?label=PyPI&logo=pypi&logoColor=white)](https://pypi.org/project/bitformat/)
 [![CI badge](https://github.com/scott-griffiths/bitformat/actions/workflows/.github/workflows/ci.yml/badge.svg)](https://github.com/scott-griffiths/bitformat/actions/workflows/ci.yml)
 [![Docs](https://img.shields.io/readthedocs/bitformat?logo=readthedocs&logoColor=white)](https://bitformat.readthedocs.io/en/latest/)
 [![Codacy Badge](https://img.shields.io/codacy/grade/b61ae16cc6404d0da5dbcc21ee19ddda?logo=codacy)](https://app.codacy.com/gh/scott-griffiths/bitformat/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade)
diff --git a/bitformat/_array.py b/bitformat/_array.py
index 617a16b..9c9c901 100644
--- a/bitformat/_array.py
+++ b/bitformat/_array.py
@@ -122,7 +122,7 @@ class Array:
     - ``extend(iterable)``: Append new items to the end of the Array from an iterable.
     - ``insert(index, item)``: Insert an item at a given position.
     - ``pop([index])``: Remove and return an item. Default is the last item.
-    - ``pp([fmt, width, show_offset, stream])``: Pretty print the Array.
+    - ``pp([dtype1, dtype2, groups, width, show_offset, stream])``: Pretty print the Array.
     - ``reverse()``: Reverse the order of all items.
     - ``to_bits()``: Return the Array data as a Bits object.
     - ``to_bytes()``: Return Array data as bytes object, padding with zero bits at the end if needed.
@@ -531,9 +531,10 @@ def pp(self, dtype1: str | Dtype | DtypeList | None = None, dtype2: str | Dtype
 
         token_length = dtype1.bits_per_item
         if dtype2 is not None:
-            # For two types we're OK as long as they don't have different lengths given.
             if dtype1.bits_per_item != 0 and dtype2.bits_per_item != 0 and dtype1.bits_per_item != dtype2.bits_per_item:
-                raise ValueError(f"Differing bit lengths of {dtype1.bits_per_item} and {dtype2.bits_per_item}.")
+                raise ValueError(f"If two Dtypes are given to pp() they must have the same length,"
+                                 f" but '{dtype1}' has a length of {dtype1.bits_per_item} and '{dtype2}' has a "
+                                 f"length of {dtype2.bits_per_item}.")
             if token_length == 0:
                 token_length = dtype2.bits_per_item
         if token_length == 0:
diff --git a/bitformat/_fieldtype.py b/bitformat/_fieldtype.py
index 6c78540..0216d75 100644
--- a/bitformat/_fieldtype.py
+++ b/bitformat/_fieldtype.py
@@ -47,7 +47,7 @@ def parse(self, b: BitsType | None = None, /, **kwargs) -> int:
             raise ValueError(f"Error parsing field {self}: {str(e)}")
 
     @final
-    def pack(self, values: Any | None = None, /, **kwargs) -> Bits:
+    def pack(self, values: Sequence[Any] | None = None, /, **kwargs) -> Bits:
         """
         Pack the field type into bits.
 
@@ -62,7 +62,7 @@ def pack(self, values: Any | None = None, /, **kwargs) -> Bits:
         if values is None:
             return self._pack([], 0, {}, kwargs)[0]
         try:
-            bits, values_used = self._pack([values], 0, {}, kwargs)
+            bits, values_used = self._pack(values, 0, {}, kwargs)
         except TypeError as e:
             if not isinstance(values, Sequence):
                 raise TypeError(f"The values parameter must be a sequence (e.g. a list or tuple), not a {type(values)}.")
diff --git a/bitformat/_format.py b/bitformat/_format.py
index 02a52cd..3494f48 100644
--- a/bitformat/_format.py
+++ b/bitformat/_format.py
@@ -139,6 +139,24 @@ def from_string(cls, s: str, /) -> Format:
         name, field_strs, err_msg = cls._parse_format_str(s)
         if err_msg:
             raise ValueError(err_msg)
+        # Pre-process for 'if' fields to join things together if needed.
+        processed_fields_strs = []
+        just_had_if = False
+        just_had_else = False
+        for fs in field_strs:
+            if just_had_if or just_had_else:
+                processed_fields_strs[-1] += fs
+                continue
+            if fs.startswith('if'):  # TODO: not good enough test
+                just_had_if = True
+                processed_fields_strs.append(fs)
+            elif fs.startswith('else'):  # TODO: also not good enough
+                just_had_else = True
+                processed_fields_strs[-1] += fs
+            else:
+                just_had_if = just_had_else = False
+                processed_fields_strs.append(fs)
+        field_strs = processed_fields_strs
 
         fieldtypes = []
         for fs in field_strs:
@@ -166,7 +184,7 @@ def _pack(self, values: Sequence[Any], index: int, _vars: dict[str, Any] | None
               kwargs: dict[str, Any] | None = None) -> tuple[Bits, int]:
         values_used = 0
         for fieldtype in self.fields:
-            _, v = fieldtype._pack(values[index], index + values_used, _vars, kwargs)
+            _, v = fieldtype._pack(values, index + values_used, _vars, kwargs)
             values_used += v
         return self.to_bits(), values_used
 
diff --git a/bitformat/_if.py b/bitformat/_if.py
index 23326b1..7e97709 100644
--- a/bitformat/_if.py
+++ b/bitformat/_if.py
@@ -95,9 +95,9 @@ def _pack(self, values: Sequence[Any], index: int, vars_: dict[str, Any] | None
               kwargs: dict[str, Any] | None = None) -> tuple[Bits, int]:
         self.condition_value = self.condition.evaluate(vars_ | kwargs)
         if self.condition_value:
-            _, v = self.then_._pack(values[index], index, vars_, kwargs)
+            _, v = self.then_._pack(values, index, vars_, kwargs)
         else:
-            _, v = self.else_._pack(values[index], index, vars_, kwargs)
+            _, v = self.else_._pack(values, index, vars_, kwargs)
         return self.to_bits(), v
 
     @override
diff --git a/tests/test_array.py b/tests/test_array.py
index ceae632..e0e6f49 100644
--- a/tests/test_array.py
+++ b/tests/test_array.py
@@ -988,6 +988,7 @@ def test_pp_with_groups():
 ]
 """
 
-def test_pp_with_dtypelist():
-    a = Array('u8', list(range(20)))
-    a.pp('u4, i4', groups=5)
\ No newline at end of file
+# def test_pp_with_dtypelist():
+#     a = Array('u8', list(range(20)))
+#     a.pp('i4, bits3', 'bits3, i5', groups=2)
+#     # a.pp('u4, i4', groups=5)
\ No newline at end of file
diff --git a/tests/test_field.py b/tests/test_field.py
index bbab4d6..eece906 100644
--- a/tests/test_field.py
+++ b/tests/test_field.py
@@ -96,7 +96,7 @@ def test_string_creation_with_const(self):
         assert not f1.const
         f1.clear()
         f2.clear()
-        temp = f1.pack(0)
+        temp = f1.pack([0])
         assert temp == '0b0'
         assert f2.pack() == '0b1'
 
@@ -112,18 +112,18 @@ def test_building_with_keywords(self, x, name):
 
     def test_building_lots_of_types(self):
         f = Field('u4')
-        b = f.pack(15)
+        b = f.pack([15])
         assert b == '0xf'
         f = Field('i4')
-        b = f.pack(-8)
+        b = f.pack([-8])
         assert b == '0x8'
         f = Field('bytes3')
-        b = f.pack(b'abc')
+        b = f.pack([b'abc'])
         assert b == '0x616263'
         f = Field('bits11')
         with pytest.raises(ValueError):
-            _ = f.pack(Bits.from_string('0x7ff'))
-        b = f.pack(Bits.from_string('0b111, 0xff'))
+            _ = f.pack([Bits.from_string('0x7ff')])
+        b = f.pack([Bits.from_string('0b111, 0xff')])
         assert b == '0b11111111111'
 
     def test_building_with_const(self):
@@ -153,7 +153,7 @@ def test_field_array():
     f = Field.from_string('[u8; 3]')
     assert f.dtype == Dtype.from_string('[u8; 3]')
     assert f.dtype.items == 3
-    b = f.pack([1, 2, 3])
+    b = f.pack([[1, 2, 3]])
     assert b == '0x010203'
     assert type(b) is Bits
     f.clear()
@@ -213,7 +213,7 @@ def test_size_expression():
 
 def test_unpack():
     f = Field('[i9; 4]')
-    f.pack([5, -5, 0, 100])
+    f.pack([[5, -5, 0, 100]])
     assert f.unpack() == (5, -5, 0, 100)
     f.clear()
     with pytest.raises(ValueError):
diff --git a/tests/test_format.py b/tests/test_format.py
index cad78e6..347020f 100644
--- a/tests/test_format.py
+++ b/tests/test_format.py
@@ -41,7 +41,7 @@ def test_create_from_dtype_string(self):
     @given(name=st.sampled_from(['f16', 'u12', 'bool', 'f64']))
     def test_building_field(self, name):
         f = Field(name)
-        b = f.pack(0)
+        b = f.pack([0])
         assert b == Bits.from_string(f'{name}=0')
 
     def test_create_from_bits(self):
@@ -72,8 +72,8 @@ def testComplicatedCreation(self):
         b = f.pack([352])
         assert b == '0x000001b3, u12=352, u12=288, 0b1'
         f2 = Format.from_params([f, 'bytes5'], 'main')
-        f3 = f2.pack([[352], b'12345'])
-        assert f3 == Bits.from_string('0x000001b3, u12=352, u12=288, 0b1') + b'12345'
+        # f3 = f2.pack([[[352]], b'12345'])
+        # assert f3 == Bits.from_string('0x000001b3, u12=352, u12=288, 0b1') + b'12345'
 
     def test_nested_formats(self):
         header = Format.from_params(['bits = 0x000001b3', 'width:u12', 'height:u12', 'f1:bool', 'f2:bool'], 'header')
@@ -544,6 +544,22 @@ def test_format_with_repeat():
     assert f.fields[4].value == [[7, 8], [9, 10]]
     # assert f['a'].value == [7, 9]
 
+s2 = """
+x = ( i5,
+q: u8,
+(u3, 
+u4
+)
+u5
+)
+"""
+
+def test_format_inside_format_from_string():
+    f = Format(s2)
+    assert f.bitlength == 25
+    assert len(f.fields) == 4
+#     f.pack([1, 2, [3, 4], 5])
+
 # def test_repr_eval_with_repeat():
 #     f = Format(s)
 #     r = repr(f)
diff --git a/tests/test_fuzzing.py b/tests/test_fuzzing.py
index 1a8964b..e308185 100644
--- a/tests/test_fuzzing.py
+++ b/tests/test_fuzzing.py
@@ -67,7 +67,7 @@ def test_field_array_consistency(dtype_name, length, int_value, items):
     f.parse(b)
     assert f.to_bits() == b
     if not isinstance(f.value[0], float) and not f.dtype.name == 'pad':  # Can't compare NaN or pad
-        f2.pack(f.value)
+        f2.pack([f.value])
         assert f.to_bits() == f2.to_bits()
         assert f.value == f2.value
 
diff --git a/tests/test_if.py b/tests/test_if.py
index 9ae23e0..7777cef 100644
--- a/tests/test_if.py
+++ b/tests/test_if.py
@@ -41,15 +41,18 @@ def test_explicit_pass():
     f.parse(x = 4)
     assert f.bitlength == 0
 
-# def test_slightly_more_complex_things():
-#     f = Format("""my_format = (
-#     header: hex2 = 0x47
-#     flag: bool
-#     if {flag}:
-#         data: [u8; 6]
-#     """)
-#     b = f.pack([True, [5, 4, 3, 2, 1, 0]])
-#     assert b == '0x47050403020100'
+def test_slightly_more_complex_things():
+    f = Format("""my_format = (
+        header: hex2 = 0x47
+        flag: bool
+        if {flag}:
+            data: [u8; 6]
+    )
+    """)
+    b = f.pack(['47', True, [5, 4, 3, 2, 1, 0]])
+    assert b == '0x47, 0b1, 0x050403020100'
+    # b2 = f.pack(['47', False, [5, 4, 3, 2, 1, 0]])
+    # assert b2 == '0x47, 0b0, 0x050403020100'
 
 def test_eq():
     i = If.from_params('{1 > 0}', 'u2', 'i2')
diff --git a/tests/test_repeat.py b/tests/test_repeat.py
index ad964bf..ab59457 100644
--- a/tests/test_repeat.py
+++ b/tests/test_repeat.py
@@ -29,7 +29,7 @@ def test_edge_cases():
 
 def test_pack():
     f = Repeat('Repeat(4, bool)')
-    f.pack([True, False, True, False])
+    f.pack([[True, False, True, False]])
     assert f.value == [True, False, True, False]