diff --git a/platformio/builder/tools/piomisc.py b/platformio/builder/tools/piomisc.py
index 87b3bf12..ba019ec3 100644
--- a/platformio/builder/tools/piomisc.py
+++ b/platformio/builder/tools/piomisc.py
@@ -326,14 +326,12 @@ def ConfigureDebugFlags(env):
 
     debug_flags = env.ParseFlags(env.GetProjectOption("debug_build_flags"))
     env.MergeFlags(debug_flags)
-    optimization_flags = [f for f in debug_flags.get("CCFLAGS", []) if f.startswith(
-        ("-O", "-g"))]
+    optimization_flags = [
+        f for f in debug_flags.get("CCFLAGS", []) if f.startswith(("-O", "-g"))
+    ]
 
     if optimization_flags:
-        env.AppendUnique(
-            ASFLAGS=optimization_flags,
-            LINKFLAGS=optimization_flags
-        )
+        env.AppendUnique(ASFLAGS=optimization_flags, LINKFLAGS=optimization_flags)
 
 
 def ConfigureTestTarget(env):
diff --git a/tests/test_builder.py b/tests/test_builder.py
index 6e73da0a..f220e50c 100644
--- a/tests/test_builder.py
+++ b/tests/test_builder.py
@@ -136,8 +136,11 @@ int main() {
     for line in build_output.split("\n"):
         if line.startswith("gcc"):
             assert all(line.count(flag) == 1 for flag in ("-Og", "-g2", "-ggdb2"))
-            assert all(line.count("-%s%d" % (flag, level)) == 0 for flag in (
-                "O", "g", "ggdb") for level in (0, 1, 3))
+            assert all(
+                line.count("-%s%d" % (flag, level)) == 0
+                for flag in ("O", "g", "ggdb")
+                for level in (0, 1, 3)
+            )
             assert "-Os" not in line
 
 
@@ -167,6 +170,9 @@ int main() {
     for line in build_output.split("\n"):
         if line.startswith("gcc"):
             assert all(line.count(f) == 1 for f in custom_debug_build_flags)
-            assert all(line.count("-%s%d" % (flag, level)) == 0 for flag in (
-                "O", "g", "ggdb") for level in (0, 1, 2))
+            assert all(
+                line.count("-%s%d" % (flag, level)) == 0
+                for flag in ("O", "g", "ggdb")
+                for level in (0, 1, 2)
+            )
             assert all("-O%s" % optimization not in line for optimization in ("g", "s"))