diff --git a/opts/envfile_test.go b/opts/envfile_test.go
index bda9dcb6e7..f875707a5e 100644
--- a/opts/envfile_test.go
+++ b/opts/envfile_test.go
@@ -100,7 +100,7 @@ func TestParseEnvFileBadlyFormattedFile(t *testing.T) {
 	if _, ok := err.(ErrBadKey); !ok {
 		t.Fatalf("Expected an ErrBadKey, got [%v]", err)
 	}
-	expectedMessage := "poorly formatted environment: variable 'f   ' has white spaces"
+	expectedMessage := "poorly formatted environment: variable 'f   ' contains whitespaces"
 	if err.Error() != expectedMessage {
 		t.Fatalf("Expected [%v], got [%v]", expectedMessage, err.Error())
 	}
@@ -134,7 +134,7 @@ another invalid line`
 	if _, ok := err.(ErrBadKey); !ok {
 		t.Fatalf("Expected an ErrBadKey, got [%v]", err)
 	}
-	expectedMessage := "poorly formatted environment: variable 'first line' has white spaces"
+	expectedMessage := "poorly formatted environment: variable 'first line' contains whitespaces"
 	if err.Error() != expectedMessage {
 		t.Fatalf("Expected [%v], got [%v]", expectedMessage, err.Error())
 	}
diff --git a/opts/file.go b/opts/file.go
index 96c0c7b84e..2346cc1670 100644
--- a/opts/file.go
+++ b/opts/file.go
@@ -51,7 +51,7 @@ func parseKeyValueFile(filename string, emptyFn func(string) (string, bool)) ([]
 			// trim the front of a variable, but nothing else
 			variable := strings.TrimLeft(data[0], whiteSpaces)
 			if strings.ContainsAny(variable, whiteSpaces) {
-				return []string{}, ErrBadKey{fmt.Sprintf("variable '%s' has white spaces", variable)}
+				return []string{}, ErrBadKey{fmt.Sprintf("variable '%s' contains whitespaces", variable)}
 			}
 			if len(variable) == 0 {
 				return []string{}, ErrBadKey{fmt.Sprintf("no variable name on line '%s'", line)}
diff --git a/opts/opts.go b/opts/opts.go
index 7e10a0c4f5..765548f6b9 100644
--- a/opts/opts.go
+++ b/opts/opts.go
@@ -281,10 +281,10 @@ func ValidateLabel(val string) (string, error) {
 	arr := strings.SplitN(val, "=", 2)
 	key := strings.TrimLeft(arr[0], whiteSpaces)
 	if key == "" {
-		return "", fmt.Errorf("empty label name: '%s'", val)
+		return "", fmt.Errorf("invalid label '%s': empty name", val)
 	}
 	if strings.ContainsAny(key, whiteSpaces) {
-		return "", fmt.Errorf("label '%s' has white spaces", key)
+		return "", fmt.Errorf("label '%s' contains whitespaces", key)
 	}
 	return val, nil
 }
diff --git a/opts/opts_test.go b/opts/opts_test.go
index 664c1010d2..4d5ef1749e 100644
--- a/opts/opts_test.go
+++ b/opts/opts_test.go
@@ -184,17 +184,17 @@ func TestValidateLabel(t *testing.T) {
 	}{
 		{
 			name:        "empty",
-			expectedErr: `empty label name: ''`,
+			expectedErr: `invalid label '': empty name`,
 		},
 		{
 			name:        "whitespace only ",
 			value:       " ",
-			expectedErr: `empty label name: ' '`,
+			expectedErr: `invalid label ' ': empty name`,
 		},
 		{
 			name:        "whitespace around equal-sign",
 			value:       " = ",
-			expectedErr: `empty label name: ' = '`,
+			expectedErr: `invalid label ' = ': empty name`,
 		},
 		{
 			name:  "leading whitespace",
@@ -203,12 +203,12 @@ func TestValidateLabel(t *testing.T) {
 		{
 			name:        "whitespaces in key without value",
 			value:       "this is a label without value",
-			expectedErr: `label 'this is a label without value' has white spaces`,
+			expectedErr: `label 'this is a label without value' contains whitespaces`,
 		},
 		{
 			name:        "whitespaces in key",
 			value:       "this is a label=value",
-			expectedErr: `label 'this is a label' has white spaces`,
+			expectedErr: `label 'this is a label' contains whitespaces`,
 		},
 		{
 			name:  "whitespaces in value",
@@ -229,7 +229,7 @@ func TestValidateLabel(t *testing.T) {
 		{
 			name:        "no key",
 			value:       "=label",
-			expectedErr: `empty label name: '=label'`,
+			expectedErr: `invalid label '=label': empty name`,
 		},
 		{
 			name:  "empty value",