diff --git a/pint_pandas/pint_array.py b/pint_pandas/pint_array.py
index 486ce53..6568e14 100644
--- a/pint_pandas/pint_array.py
+++ b/pint_pandas/pint_array.py
@@ -308,6 +308,8 @@ def __init__(self, values, dtype=None, copy=False):
         # infer subdtype from values if not given in dtype
         if isinstance(dtype, str) and dtype.count("[") <= 1:
             _dtype = PintType(dtype)
+            if isinstance(values, _Quantity):
+                values = values.m_as(_dtype.units)
             values = pd.array(values, copy=copy)
             dtype = PintType(units=_dtype.units, subdtype=values.dtype)
         # infer units and subdtype from values if no dtype given
diff --git a/pint_pandas/testsuite/test_pandas_interface.py b/pint_pandas/testsuite/test_pandas_interface.py
index 2cddcbd..63d0597 100644
--- a/pint_pandas/testsuite/test_pandas_interface.py
+++ b/pint_pandas/testsuite/test_pandas_interface.py
@@ -92,7 +92,7 @@ def test_df_operations(self):
     def test_dequantify(self):
         df = pd.DataFrame(
             {
-                "no_unit_column": pd.Series([i for i in range(4)], dtype=float),
+                "no_unit_column": pd.Series([i for i in range(4)], dtype="Float64"),
                 "pintarray_column": pd.Series(
                     [1.0, 2.0, 2.0, 3.0], dtype="pint[lbf ft]"
                 ),
@@ -100,7 +100,7 @@ def test_dequantify(self):
         )
         expected = pd.DataFrame(
             {
-                ("no_unit_column", "No Unit"): {0: 0.0, 1: 1.0, 2: 2.0, 3: 3.0},
+                ("no_unit_column", "No Unit"):  pd.Series({0: 0.0, 1: 1.0, 2: 2.0, 3: 3.0}, dtype="Float64"),
                 ("pintarray_column", "foot * force_pound"): pd.Series(
                     {
                         0: 1.0,
@@ -127,12 +127,12 @@ def test_quantify(self):
                     2: 2.0,
                     3: 3.0,
                 },
-            }
+            }, dtype="Float64"
         )
         df.columns.names = [None, "unit"]
         expected = pd.DataFrame(
             {
-                "no_unit_column": pd.Series([i for i in range(4)], dtype=float),
+                "no_unit_column": pd.Series([i for i in range(4)], dtype="Float64"),
                 "pintarray_column": pd.Series(
                     [1.0, 2.0, 2.0, 3.0], dtype="pint[lbf ft]"
                 ),
@@ -145,7 +145,7 @@ def test_quantify(self):
         def test_to_base_units(self):
             df = pd.DataFrame(
                 {
-                    "no_unit_column": pd.Series([i for i in range(4)], dtype=float),
+                    "no_unit_column": pd.Series([i for i in range(4)], dtype="Float64"),
                     "pintarray_column": pd.Series(
                         [1.0, 2.0, 2.0, 3.0], dtype="pint[lbf ft]"
                     ),
@@ -155,7 +155,7 @@ def test_to_base_units(self):
 
             expected = pd.DataFrame(
                 {
-                    "no_unit_column": pd.Series([i for i in range(4)], dtype=float),
+                    "no_unit_column": pd.Series([i for i in range(4)], dtype="Float64"),
                     "pintarray_column": pd.Series(
                         [
                             1.3558179483314006,