diff --git a/app/src/main/java/protect/card_locker/LoyaltyCardEditActivity.java b/app/src/main/java/protect/card_locker/LoyaltyCardEditActivity.java
index 47529ac86..cb5187a60 100644
--- a/app/src/main/java/protect/card_locker/LoyaltyCardEditActivity.java
+++ b/app/src/main/java/protect/card_locker/LoyaltyCardEditActivity.java
@@ -369,7 +369,7 @@ public class LoyaltyCardEditActivity extends CatimaAppCompatActivity implements
                 generateIcon(storeName);
 
                 if (storeName.length() == 0) {
-                    storeFieldEdit.setError(getString(R.string.field_may_not_be_empty));
+                    storeFieldEdit.setError(getString(R.string.field_must_not_be_empty));
                 } else {
                     storeFieldEdit.setError(null);
                 }
@@ -502,7 +502,7 @@ public class LoyaltyCardEditActivity extends CatimaAppCompatActivity implements
                 updateTempState(LoyaltyCardField.cardId, s.toString());
 
                 if (s.length() == 0) {
-                    cardIdFieldView.setError(getString(R.string.field_may_not_be_empty));
+                    cardIdFieldView.setError(getString(R.string.field_must_not_be_empty));
                 } else {
                     cardIdFieldView.setError(null);
                 }
@@ -1492,7 +1492,7 @@ public class LoyaltyCardEditActivity extends CatimaAppCompatActivity implements
         boolean hasError = false;
 
         if (tempLoyaltyCard.store.isEmpty()) {
-            storeFieldEdit.setError(getString(R.string.field_may_not_be_empty));
+            storeFieldEdit.setError(getString(R.string.field_must_not_be_empty));
 
             // Focus element
             tabs.selectTab(tabs.getTabAt(0));
@@ -1502,7 +1502,7 @@ public class LoyaltyCardEditActivity extends CatimaAppCompatActivity implements
         }
 
         if (tempLoyaltyCard.cardId.isEmpty()) {
-            cardIdFieldView.setError(getString(R.string.field_may_not_be_empty));
+            cardIdFieldView.setError(getString(R.string.field_must_not_be_empty));
 
             // Focus element if first error element
             if (!hasError) {
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index e3c45c987..01dd0b481 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -148,7 +148,7 @@
         <item quantity="other"><xliff:g>%d</xliff:g> cards</item>
     </plurals>
     <string name="group_name_already_in_use">Group name already in use</string>
-    <string name="group_name_is_empty">Group name cannot be empty</string>
+    <string name="group_name_is_empty">Group name must not be empty</string>
     <string name="group_updated">Group updated</string>
     <string name="all">All</string>
     <string name="deleteConfirmationGroup">Delete group?</string>
@@ -331,5 +331,5 @@
     <string name="action_display_options">Display options</string>
     <string name="show_archived_cards">Show archived cards</string>
     <string name="view_online">View online</string>
-    <string name="field_may_not_be_empty">Field may not be empty</string>
+    <string name="field_must_not_be_empty">Field must not be empty</string>
 </resources>