diff --git a/buildroot/share/PlatformIO/scripts/preflight-checks.py b/buildroot/share/PlatformIO/scripts/preflight-checks.py
index e4bcc83cb3..40a31417e1 100644
--- a/buildroot/share/PlatformIO/scripts/preflight-checks.py
+++ b/buildroot/share/PlatformIO/scripts/preflight-checks.py
@@ -86,10 +86,12 @@ if pioutil.is_pio_build():
 		#
 		# Give warnings on every build
 		#
-		srcpath = os.path.join(env['PROJECT_BUILD_DIR'], build_env, "src", "src")
-		warnfile = os.path.join(srcpath, "inc", "Warnings.cpp.o")
-		if os.path.exists(warnfile):
-			os.remove(warnfile)
+		build_dir = os.path.join(env['PROJECT_BUILD_DIR'], build_env);
+		for outdir in [ build_dir, os.path.join(build_dir, "debug") ]:
+			for wext in [ ".cpp", "" ]:
+				warnfile = os.path.join(outdir, "src", "src", "inc", "Warnings" + wext + ".o")
+				if os.path.exists(warnfile):
+					os.remove(warnfile)
 
 		#
 		# Rebuild 'settings.cpp' for EEPROM_INIT_NOW