diff --git a/result.go b/result.go
index d427a6d..d6852b2 100644
--- a/result.go
+++ b/result.go
@@ -2,7 +2,6 @@ package models
 
 import (
 	"errors"
-	"git.sch9.ru/new_gate/ms-tester/internal/lib"
 )
 
 type Result int32
@@ -10,12 +9,12 @@ type Result int32
 const (
 	NotTested               Result = 1 // change only with schema change
 	Accepted                Result = 2
-    WrongAnswer             Result = 3
-    PresentationError       Result = 4
+	WrongAnswer             Result = 3
+	PresentationError       Result = 4
 	CompilationError        Result = 5
 	MemoryLimitExceeded     Result = 6
 	TimeLimitExceeded       Result = 7
-    RuntimeError            Result = 8
+	RuntimeError            Result = 8
 	SystemFailDuringTesting Result = 9
 	Testing                 Result = 10
 )
@@ -27,5 +26,5 @@ func (result Result) Valid() error {
 	case NotTested, Accepted, TimeLimitExceeded, MemoryLimitExceeded, CompilationError, SystemFailDuringTesting:
 		return nil
 	}
-	return lib.ServiceError(ErrBadResult, lib.ErrValidationFailed, "bad result")
+	return ErrBadResult
 }
diff --git a/role.go b/role.go
index a48cca8..d978058 100644
--- a/role.go
+++ b/role.go
@@ -2,7 +2,6 @@ package models
 
 import (
 	"errors"
-	"git.sch9.ru/new_gate/ms-tester/internal/lib"
 )
 
 type Role int32
@@ -45,7 +44,7 @@ func (role Role) Valid() error {
 	case RoleSpectator, RoleParticipant, RoleModerator, RoleAdmin:
 		return nil
 	}
-	return lib.ServiceError(ErrBadRole, lib.ErrValidationFailed, "bad role")
+	return ErrBadRole
 }
 
 func (role Role) AsPointer() *Role {
diff --git a/testgroup.go b/testgroup.go
index f102a0c..f48e587 100644
--- a/testgroup.go
+++ b/testgroup.go
@@ -2,7 +2,6 @@ package models
 
 import (
 	"errors"
-	"git.sch9.ru/new_gate/ms-tester/internal/lib"
 )
 
 type TestingStrategy int32
@@ -30,5 +29,5 @@ func (ts TestingStrategy) Valid() error {
 	case EachTestTS, CompleteGroupTS:
 		return nil
 	}
-	return lib.ServiceError(ErrBadTestingStrategy, lib.ErrValidationFailed, "bad testing strategy")
+	return ErrBadTestingStrategy
 }