diff --git a/src/Lidarr.Api.V1/Profiles/Release/ReleaseProfileModule.cs b/src/Lidarr.Api.V1/Profiles/Release/ReleaseProfileModule.cs
index 9718c6728..1f7ca6daf 100644
--- a/src/Lidarr.Api.V1/Profiles/Release/ReleaseProfileModule.cs
+++ b/src/Lidarr.Api.V1/Profiles/Release/ReleaseProfileModule.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 using FluentValidation;
 using Lidarr.Http;
 using NzbDrone.Common.Extensions;
@@ -34,6 +35,11 @@ namespace Lidarr.Api.V1.Profiles.Release
                 {
                     context.AddFailure(nameof(ReleaseProfile.IndexerId), "Indexer does not exist");
                 }
+
+                if (restriction.Preferred.Any(p => p.Key.IsNullOrWhiteSpace()))
+                {
+                    context.AddFailure("Preferred", "Term cannot be empty or consist of only spaces");
+                }
             });
         }