diff --git a/cmd/crossplane/main.go b/cmd/crossplane/main.go
index d3ee38c..ae8d2d6 100644
--- a/cmd/crossplane/main.go
+++ b/cmd/crossplane/main.go
@@ -141,7 +141,10 @@ func configFlag(args []string) (string, error) {
 			continue
 		}
 
-		if v := strings.TrimPrefix(a, "--config="); v != "" {
+		if v, ok := strings.CutPrefix(a, "--config="); ok {
+			if v == "" {
+				return "", errors.New("flag --config requires a value")
+			}
 			return v, nil
 		}
 
diff --git a/cmd/crossplane/main_test.go b/cmd/crossplane/main_test.go
new file mode 100644
index 0000000..1409c39
--- /dev/null
+++ b/cmd/crossplane/main_test.go
@@ -0,0 +1,83 @@
+/*
+Copyright 2026 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+)
+
+func TestConfigFlag(t *testing.T) {
+	type want struct {
+		path string
+		err  error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   []string
+		want   want
+	}{
+		"Empty": {
+			reason: "No args should yield no path and no error.",
+			args:   nil,
+		},
+		"NoConfigFlag": {
+			reason: "Argv without --config should yield no path and no error.",
+			args:   []string{"version"},
+		},
+		"EqualsForm": {
+			reason: "--config=PATH should return PATH.",
+			args:   []string{"--config=/tmp/config.yaml"},
+			want:   want{path: "/tmp/config.yaml"},
+		},
+		"SpaceForm": {
+			reason: "--config PATH should return PATH from the next argv.",
+			args:   []string{"--config", "/tmp/config.yaml"},
+			want:   want{path: "/tmp/config.yaml"},
+		},
+		"EmptyEquals": {
+			reason: "--config= is an explicitly empty value and should return an error.",
+			args:   []string{"--config="},
+			want:   want{err: cmpopts.AnyError},
+		},
+		"MissingValue": {
+			reason: "Trailing --config with no following argv should return an error.",
+			args:   []string{"--config"},
+			want:   want{err: cmpopts.AnyError},
+		},
+		"FirstWins": {
+			reason: "If --config appears more than once, the first occurrence wins.",
+			args:   []string{"--config=/first.yaml", "--config=/second.yaml"},
+			want:   want{path: "/first.yaml"},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			got, err := configFlag(tc.args)
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\nconfigFlag(%v): -want err, +got err:\n%s", tc.reason, tc.args, diff)
+			}
+			if diff := cmp.Diff(tc.want.path, got); diff != "" {
+				t.Errorf("\n%s\nconfigFlag(%v): -want, +got:\n%s", tc.reason, tc.args, diff)
+			}
+		})
+	}
+}