diff --git a/testutil/testutil.go b/testutil/testutil.go
index d343639..4e529f3 100644
--- a/testutil/testutil.go
+++ b/testutil/testutil.go
@@ -86,6 +86,19 @@ func ParseCliCaseArg() []int {
 	return ret
 }
 
+type testCaseParseError struct {
+	Line int
+	Err  error
+}
+
+func (e *testCaseParseError) Error() string {
+	return fmt.Sprintf("line %v: %v", e.Line, e.Err)
+}
+
+func (e *testCaseParseError) Unwrap() error {
+	return e.Err
+}
+
 // ParseTestCaseFile parses the contents of the given test case file
 // and reurns the test cases found inside.
 //
@@ -133,7 +146,7 @@ func ParseCliCaseArg() []int {
 func ParseTestCaseFile(filename string) ([]MarkdownTestCase, error) {
 	fp, err := os.Open(filename)
 	if err != nil {
-		panic(err)
+		return nil, err
 	}
 	defer fp.Close()
 
@@ -147,6 +160,15 @@ func ParseTestCaseFile(filename string) ([]MarkdownTestCase, error) {
 	}
 	cases := []MarkdownTestCase{}
 	line := 0
+
+	// Builds a testCaseParseError for the curent line.
+	parseErrorf := func(msg string, args ...interface{}) error {
+		return &testCaseParseError{
+			Line: line,
+			Err:  fmt.Errorf(msg, args...),
+		}
+	}
+
 	for scanner.Scan() {
 		line++
 		if util.IsBlank([]byte(scanner.Text())) {
@@ -162,23 +184,23 @@ func ParseTestCaseFile(filename string) ([]MarkdownTestCase, error) {
 			c.No, err = strconv.Atoi(scanner.Text())
 		}
 		if err != nil {
-			panic(fmt.Sprintf("%s: invalid case No at line %d", filename, line))
+			return nil, parseErrorf("invalid case No: %w", err)
 		}
 		if !scanner.Scan() {
-			panic(fmt.Sprintf("%s: invalid case at line %d", filename, line))
+			return nil, parseErrorf("invalid case: expected content after case No")
 		}
 		line++
 		matches := optionsRegexp.FindAllStringSubmatch(scanner.Text(), -1)
 		if len(matches) != 0 {
 			err = json.Unmarshal([]byte(matches[0][1]), &c.Options)
 			if err != nil {
-				panic(fmt.Sprintf("%s: invalid options at line %d", filename, line))
+				return nil, parseErrorf("invalid options: %w", err)
 			}
 			scanner.Scan()
 			line++
 		}
 		if scanner.Text() != attributeSeparator {
-			panic(fmt.Sprintf("%s: invalid separator '%s' at line %d", filename, scanner.Text(), line))
+			return nil, parseErrorf("invalid separator %q", scanner.Text())
 		}
 		buf := []string{}
 		for scanner.Scan() {
diff --git a/testutil/testutil_test.go b/testutil/testutil_test.go
index 87e0975..541a993 100644
--- a/testutil/testutil_test.go
+++ b/testutil/testutil_test.go
@@ -1,6 +1,7 @@
 package testutil
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -102,3 +103,103 @@ func TestParseTestCaseFile(t *testing.T) {
 		})
 	}
 }
+
+func TestParseTestCaseFile_Errors(t *testing.T) {
+	tests := []struct {
+		desc   string
+		give   string // contents of the test file
+		errMsg string
+	}{
+		{
+			desc: "bad number/no description",
+			give: strings.Join([]string{
+				"1 not a number",
+				"//- - - - - - - - -//",
+				"world",
+				"//- - - - - - - - -//",
+				"<p>world</p>",
+				"//= = = = = = = = = = = = = = = = = = = = = = = =//",
+			}, "\n"),
+			errMsg: "line 1: invalid case No",
+		},
+		{
+			desc: "bad number/description",
+			give: strings.Join([]string{
+				"1 not a number:description",
+				"//- - - - - - - - -//",
+				"world",
+				"//- - - - - - - - -//",
+				"<p>world</p>",
+				"//= = = = = = = = = = = = = = = = = = = = = = = =//",
+			}, "\n"),
+			errMsg: "line 1: invalid case No",
+		},
+		{
+			desc: "eof after number",
+			give: strings.Join([]string{
+				"1",
+			}, "\n"),
+			errMsg: "line 1: invalid case: expected content after",
+		},
+		{
+			desc: "bad options",
+			give: strings.Join([]string{
+				"3",
+				`OPTIONS: {not valid JSON}`,
+				"//- - - - - - - - -//",
+				"world",
+				"//- - - - - - - - -//",
+				"<p>world</p>",
+				"//= = = = = = = = = = = = = = = = = = = = = = = =//",
+			}, "\n"),
+			errMsg: "line 2: invalid options:",
+		},
+		{
+			desc: "bad separator",
+			give: strings.Join([]string{
+				"3",
+				"// not the right separator //",
+			}, "\n"),
+			errMsg: `line 2: invalid separator "// not the right separator //"`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			filename := filepath.Join(t.TempDir(), "give.txt")
+			if err := os.WriteFile(filename, []byte(tt.give), 0o644); err != nil {
+				t.Fatal(err)
+			}
+
+			cases, err := ParseTestCaseFile(filename)
+			if err == nil {
+				t.Fatalf("expected error, got:\n%#v", cases)
+			}
+
+			if got := err.Error(); !strings.Contains(got, tt.errMsg) {
+				t.Errorf("unexpected error message:")
+				t.Errorf("             got = %v", got)
+				t.Errorf("does not contain = %v", tt.errMsg)
+			}
+		})
+	}
+}
+
+func TestTestCaseParseError(t *testing.T) {
+	wrapped := errors.New("great sadness")
+	err := &testCaseParseError{Line: 42, Err: wrapped}
+
+	t.Run("Error", func(t *testing.T) {
+		want := "line 42: great sadness"
+		got := err.Error()
+		if want != got {
+			t.Errorf("Error() = %q, want %q", got, want)
+		}
+	})
+
+	t.Run("Unwrap", func(t *testing.T) {
+		if !errors.Is(err, wrapped) {
+			t.Errorf("error %#v should unwrap to %#v", err, wrapped)
+		}
+	})
+}