diff --git a/.github/workflows/constraints.txt b/.github/workflows/constraints.txt
index cf213ae..4987e40 100644
--- a/.github/workflows/constraints.txt
+++ b/.github/workflows/constraints.txt
@@ -1,6 +1,6 @@
 pip==21.2.4
 pre-commit==2.13.0
-black==21.7b0
+black==22.3.0
 flake8==3.9.2
 reorder-python-imports==2.6.0
 pytest-timeout==1.4.2
diff --git a/pymyenergi/libbi.py b/pymyenergi/libbi.py
index d6c2838..85c9f99 100644
--- a/pymyenergi/libbi.py
+++ b/pymyenergi/libbi.py
@@ -287,12 +287,12 @@ def show(self, short_format=False):
             else:
                 ret = ret + "Disabled\n"
         else:
-            ret = ret + f"<unavailable>\n"
-        ret = ret + f"Charge target: "
+            ret = ret + "<unavailable>\n"
+        ret = ret + "Charge target: "
         if self.charge_target is not None:
             ret = ret + f"{self.charge_target}kWh\n"
         else:
-            ret = ret + f"<unavailable>\n"
+            ret = ret + "<unavailable>\n"
         ret = ret + f"CT 1 {self.ct1.name} {self.ct1.power}W phase {self.ct1.phase}\n"
         ret = ret + f"CT 2 {self.ct2.name} {self.ct2.power}W phase {self.ct2.phase}\n"
         ret = ret + f"CT 3 {self.ct3.name} {self.ct3.power}W phase {self.ct3.phase}\n"
diff --git a/requirements_dev.txt b/requirements_dev.txt
index 625e4b9..cb83934 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -1,7 +1,7 @@
 httpx
 pycognito
 pre-commit==2.13.0
-black==21.7b0
+black==22.3.0
 flake8==3.9.2
 reorder-python-imports==2.6.0
 pytest-timeout==1.4.2