diff --git a/pkg/internal/apis/config/validate.go b/pkg/internal/apis/config/validate.go
index 1aebb29418..7829cd074f 100644
--- a/pkg/internal/apis/config/validate.go
+++ b/pkg/internal/apis/config/validate.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"net"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"sigs.k8s.io/kind/pkg/errors"
@@ -171,7 +172,7 @@ func validatePortMappings(portMappings []PortMapping) error {
 		addrString := addr.String()
 
 		portProtocol := formatPortProtocol(portMapping.HostPort, portMapping.Protocol)
-		possibleErr := fmt.Errorf("%s: %s:%s", errMsg, addrString, portProtocol)
+		possibleErr := fmt.Errorf("%s: %s/%s", errMsg, net.JoinHostPort(addrString, strconv.Itoa(int(portMapping.HostPort))), portMapping.Protocol)
 
 		// in golang 0.0.0.0 and [::] are equivalent, convert [::] -> 0.0.0.0
 		// https://github.com/golang/go/issues/48723
diff --git a/pkg/internal/apis/config/validate_test.go b/pkg/internal/apis/config/validate_test.go
index 5b8b089c7a..41dd2353e0 100644
--- a/pkg/internal/apis/config/validate_test.go
+++ b/pkg/internal/apis/config/validate_test.go
@@ -18,7 +18,6 @@ package config
 
 import (
 	"fmt"
-	"sigs.k8s.io/kind/pkg/internal/assert"
 	"testing"
 
 	"sigs.k8s.io/kind/pkg/errors"
@@ -563,7 +562,16 @@ func TestValidatePortMappings(t *testing.T) {
 			t.Parallel()
 
 			err := validatePortMappings(tc.portMappings)
-			assert.ExpectError(t, len(tc.expectErr) > 0, err)
+
+			// the error can be:
+			// - nil, in which case we should expect no errors or fail
+			if err == nil && len(tc.expectErr) > 0 {
+				t.Errorf("Test failed, unexpected error: %s", tc.expectErr)
+			}
+
+			if err != nil && err.Error() != tc.expectErr {
+				t.Errorf("Test failed, error: %s expected error: %s", err, tc.expectErr)
+			}
 		})
 	}
 }