diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 846f162f..4cd9dfe4 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -26,36 +26,3 @@ jobs:
 
       - name: Build
         run: make build/cmd/protolint
-
-      - name: Build Docker image
-        run: docker build -t docker.io/yoheimuta/protolint:${{ github.sha }} .
-
-      - name: Run Trivy vulnerability scanner
-        uses: aquasecurity/trivy-action@0.6.2
-        with:
-          image-ref: docker.io/yoheimuta/protolint:${{ github.sha }}
-          exit-code: '1'
-          format: sarif
-          ignore-unfixed: true
-          output: trivy-results.sarif
-
-      - name: Upload Trivy scan results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@v2
-        if: always()
-        with:
-          sarif_file: trivy-results.sarif
-          wait-for-processing: true
-
-      - uses: hadolint/hadolint-action@v2.1.0
-        with:
-          dockerfile: Dockerfile
-          failure-threshold: style
-          format: sarif
-          output-file: hadolint-results.sarif
-
-      - name: Upload Hadolint scan results to GitHub Security tab
-        uses: github/codeql-action/upload-sarif@v2
-        if: always()
-        with:
-          sarif_file: hadolint-results.sarif
-          wait-for-processing: true
diff --git a/_testdata/rules/indentrule/issue_280_mix_lineending.proto b/_testdata/rules/indentrule/issue_280_mix_lineending.proto
new file mode 100644
index 00000000..9382eec5
--- /dev/null
+++ b/_testdata/rules/indentrule/issue_280_mix_lineending.proto
@@ -0,0 +1,68 @@
+// https://github.com/pseudomuto/protoc-gen-doc/blob/master/examples/proto/Booking.proto
+
+/**
+ * Booking related messages.
+ *
+ * This file is really just an example. The data model is completely
+ * fictional.
+ */
+syntax = "proto3";
+
+package com.example;
+
+import "google/api/annotations.proto";
+import "github.com/mwitkow/go-proto-validators/validator.proto";
+
+/**
+ * Represents the booking status ID.
+ */
+message BookingStatusID {
+  int32 id = 1; /// Unique booking status ID.
+}
+
+/**
+ * Represents the status of a vehicle booking.
+ */
+message BookingStatus {
+    int32 id           = 1; /// Unique booking status ID.
+  string description = 2 [(validator.field) = {string_not_empty: true, length_lt: 255}]; /// Booking status description. E.g. "Active".
+}
+
+/**
+ * Represents the booking of a vehicle.
+ *
+ * Vehicles are some cool shit. But drive carefully!
+ */
+message Booking {
+  int32 vehicle_id     = 1; /// ID of booked vehicle.
+  int32 customer_id    = 2; /// Customer that booked the vehicle.
+  BookingStatus status = 3; /// Status of the booking.
+
+  /** Has booking confirmation been sent? */
+  bool confirmation_sent = 4;
+
+  /** Has payment been received? */
+  bool payment_received = 5;
+
+  string color_preference = 6 [deprecated=true]; // Color preference of the customer.
+}
+
+// An empty message for testing
+message EmptyBookingMessage {
+}
+
+/**
+ * Service for handling vehicle bookings.
+ */
+service BookingService {
+  /// Used to book a vehicle. Pass in a Booking and a BookingStatus will be returned.
+  rpc BookVehicle (Booking) returns (BookingStatus) {
+    option (google.api.http) = {
+      post: "/api/bookings/vehicle/{vehicle_id}"
+      body: "*"
+    };
+  }
+
+  /// Used to subscribe to updates of the BookingStatus.
+  rpc BookingUpdates (BookingStatusID) returns (stream BookingStatus);
+}
diff --git a/internal/addon/rules/indentRule_test.go b/internal/addon/rules/indentRule_test.go
index 54294e75..aa71f140 100644
--- a/internal/addon/rules/indentRule_test.go
+++ b/internal/addon/rules/indentRule_test.go
@@ -216,6 +216,25 @@ Fix https://github.com/yoheimuta/protolint/issues/139`,
 				),
 			},
 		},
+		{
+			name: `handle the case that the proto has a mixture of line ending formats like LF and CRLF.
+Fix https://github.com/yoheimuta/protolint/issues/280`,
+			inputProtoPath: setting_test.TestDataPath("rules", "indentrule", "issue_280_mix_lineending.proto"),
+			wantFailures: []report.Failure{
+				report.Failuref(
+					meta.Position{
+						Filename: setting_test.TestDataPath("rules", "indentrule", "issue_280_mix_lineending.proto"),
+						Offset:   580,
+						Line:     27,
+						Column:   5,
+					},
+					"INDENT",
+					`Found an incorrect indentation style "%s". "%s" is correct.`,
+					"    ",
+					"  ",
+				),
+			},
+		},
 	}
 
 	for _, test := range tests {
diff --git a/linter/fixer/fixer.go b/linter/fixer/fixer.go
index 9af1e4db..3e063907 100644
--- a/linter/fixer/fixer.go
+++ b/linter/fixer/fixer.go
@@ -60,13 +60,14 @@ func NewBaseFixing(protoFileName string) (*BaseFixing, error) {
 	if err != nil {
 		return nil, err
 	}
-	lineEnding, err := osutil.DetectLineEnding(string(content))
-	if err != nil {
-		return nil, err
-	}
-	if len(lineEnding) == 0 {
-		lineEnding = "\n"
-	}
+
+	// Regardless of the actual dominant line ending, the fixer will go with LF
+	// because the parser recognizes only LF as a line ending.
+	//
+	// It will work for most cases like used LF, CRLF, and a mix of LF and CRLF.
+	// See also https://github.com/yoheimuta/protolint/issues/280.
+	lineEnding := "\n"
+
 	return &BaseFixing{
 		content:    content,
 		lineEnding: lineEnding,