diff --git a/http/httpErr.go b/http/httpErr.go
index fc87acb..701cfbf 100644
--- a/http/httpErr.go
+++ b/http/httpErr.go
@@ -12,10 +12,11 @@ import (
 // and a field "message" set to the `message`
 //
 // Deprecated: Use ProblemDetails or ProblemDetailsStatusOnly instead
-func HttpErr(w http.ResponseWriter, errId int, message string, code int) {
+func HttpErr(w http.ResponseWriter, errId int, message string, code int) error {
 	w.WriteHeader(code)
 	w.Header().Add("Content-Type", "application/json")
-	fmt.Fprintf(w, "{\"id\": %d, \"message\": \"%s\"}", errId, message)
+	_, err := fmt.Fprintf(w, "{\"id\": %d, \"message\": \"%s\"}", errId, message)
+	return err
 }
 
 // Write an RFC 9457 compliant problem details response
@@ -31,7 +32,7 @@ func ProblemDetails(
 	errorTitle string,
 	details *string,
 	extras map[string]any,
-) {
+) error {
 	w.Header().Add("Content-Type", "application/problem+json")
 	w.WriteHeader(statusCode)
 	data := map[string]any{
@@ -42,22 +43,20 @@ func ProblemDetails(
 	if details != nil {
 		data["detail"] = *details
 	}
-	if extras != nil {
-		for k, v := range extras {
-			if _, ok := data[k]; ok {
-				// Don't overwrite default fields
-				continue
-			}
-			data[k] = v
+	for k, v := range extras {
+		if _, ok := data[k]; ok {
+			// Don't overwrite default fields
+			continue
 		}
+		data[k] = v
 	}
 	enc := json.NewEncoder(w)
-	enc.Encode(data)
+	return enc.Encode(data)
 }
 
 // Write a simple problem details response.
 // It only provides the status code, as defined in RFC 9457, section 4.2.1
-func ProblemDetailsStatusOnly(w http.ResponseWriter, statusCode int) {
+func ProblemDetailsStatusOnly(w http.ResponseWriter, statusCode int) error {
 	w.Header().Add("Content-Type", "application/problem+json")
 	w.WriteHeader(statusCode)
 	data := map[string]any{
@@ -68,5 +67,5 @@ func ProblemDetailsStatusOnly(w http.ResponseWriter, statusCode int) {
 	}
 
 	enc := json.NewEncoder(w)
-	enc.Encode(data)
+	return enc.Encode(data)
 }