diff --git a/cmd/root_test.go b/cmd/root_test.go
index dccc2c7..1387568 100644
--- a/cmd/root_test.go
+++ b/cmd/root_test.go
@@ -211,3 +211,25 @@ Bye.`,
 		})
 	}
 }
+
+func TestIsJSON(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected bool
+	}{
+		{"{}", true},
+		{"[]", true},
+		{" {}", true},
+		{"\t[", true},
+		{"<root></root>", false},
+		{"<![CDATA[text]]>", false}, // Bug #160: should not match [ in CDATA
+		{"plain text", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			result := utils.IsJSON(tt.input)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
diff --git a/internal/utils/utils.go b/internal/utils/utils.go
index 2597b2a..7f74e06 100644
--- a/internal/utils/utils.go
+++ b/internal/utils/utils.go
@@ -519,7 +519,7 @@ func IsHTML(input string) bool {
 
 func IsJSON(input string) bool {
 	input = strings.ToLower(input)
-	matched, _ := regexp.MatchString(`\s*[{\[]`, input)
+	matched, _ := regexp.MatchString(`^\s*[{\[]`, input)
 	return matched
 }