diff --git a/teku/src/main/java/tech/pegasys/teku/cli/options/ValidatorKeysOptions.java b/teku/src/main/java/tech/pegasys/teku/cli/options/ValidatorKeysOptions.java
index f551279bf25..41a7ad9dff8 100644
--- a/teku/src/main/java/tech/pegasys/teku/cli/options/ValidatorKeysOptions.java
+++ b/teku/src/main/java/tech/pegasys/teku/cli/options/ValidatorKeysOptions.java
@@ -134,10 +134,10 @@ public void configure(TekuConfiguration.Builder builder) {
   }
 
   private List<String> parseValidatorExternalKeys(final boolean allowNoLoadedKeys) {
-    if (allowNoLoadedKeys) {
-      return validatorExternalSignerPublicKeys.stream().filter(StringUtils::isNotBlank).toList();
+    if (!allowNoLoadedKeys && validatorExternalSignerPublicKeys.isEmpty()) {
+      throw new InvalidConfigurationException("No validator external signer keys are loaded");
     }
-    return validatorExternalSignerPublicKeys;
+    return validatorExternalSignerPublicKeys.stream().filter(StringUtils::isNotBlank).toList();
   }
 
   private URL parseValidatorExternalSignerUrl() {