diff --git a/CITATION.cff b/CITATION.cff
index 1d1a083..52ebfce 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -3,8 +3,8 @@ message: "If you use this software, please cite it as below."
 
 title: "de:code"
 abstract: "DESHIMA code for data analysis"
-version: 2.16.0
-date-released: 2024-07-13
+version: 2.16.1
+date-released: 2024-07-14
 license: "MIT"
 doi: "10.5281/zenodo.3384216"
 url: "https://github.com/deshima-dev/decode"
diff --git a/README.md b/README.md
index 18a2a1e..ed44d80 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ DESHIMA code for data analysis
 ## Installation
 
 ```shell
-pip install decode==2.16.0
+pip install decode==2.16.1
 ```
 
 ## Quick look
diff --git a/decode/__init__.py b/decode/__init__.py
index 46360cf..f40c5cd 100644
--- a/decode/__init__.py
+++ b/decode/__init__.py
@@ -10,7 +10,7 @@
     "select",
     "utils",
 ]
-__version__ = "2.16.0"
+__version__ = "2.16.1"
 
 
 # submodules
diff --git a/decode/qlook.py b/decode/qlook.py
index 331194f..9ef0e85 100644
--- a/decode/qlook.py
+++ b/decode/qlook.py
@@ -1065,17 +1065,29 @@ def load_dems(
     """
     da = load.dems(dems, chunks=None)
 
+    if min_frequency is not None:
+        min_frequency = Quantity(min_frequency).to(frequency_units).value
+
+    if max_frequency is not None:
+        max_frequency = Quantity(max_frequency).to(frequency_units).value
+
     if da.frame == "altaz":
         z = np.pi / 2 - convert.units(da.lat, "rad")
         secz = cast(xr.DataArray, 1 / np.cos(z))
-
         da = da.assign_coords(
-            secz=secz.assign_attrs(
-                long_name="sec(Z)",
-                units="dimensionless",
-            )
+            secz=secz.assign_attrs(long_name="sec(Z)", units="dimensionless")
         )
 
+    da = convert.coord_units(
+        da,
+        ["d2_mkid_frequency", "frequency"],
+        frequency_units,
+    )
+    da = convert.coord_units(
+        da,
+        ["lat", "lat_origin", "lon", "lon_origin"],
+        skycoord_units,
+    )
     da = assign.scan(da, by="state")
     da = convert.frame(da, "relative")
     da = select.by(da, "d2_mkid_type", "filter")
@@ -1091,16 +1103,6 @@ def load_dems(
         min=min_frequency,
         max=max_frequency,
     )
-    da = convert.coord_units(
-        da,
-        ["d2_mkid_frequency", "frequency"],
-        frequency_units,
-    )
-    da = convert.coord_units(
-        da,
-        ["lat", "lat_origin", "lon", "lon_origin"],
-        skycoord_units,
-    )
 
     if data_type == "auto" and "units" in da.attrs:
         return da
diff --git a/pyproject.toml b/pyproject.toml
index 3f02e57..90a20a7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "decode"
-version = "2.16.0"
+version = "2.16.1"
 description = "DESHIMA code for data analysis"
 authors = [
     "Akio Taniguchi <taniguchi@a.phys.nagoya-u.ac.jp>",