diff --git a/src/Unleash/Strategies/FlexibleRolloutStrategy.cs b/src/Unleash/Strategies/FlexibleRolloutStrategy.cs
index b6f0475b..4d49aad9 100644
--- a/src/Unleash/Strategies/FlexibleRolloutStrategy.cs
+++ b/src/Unleash/Strategies/FlexibleRolloutStrategy.cs
@@ -40,7 +40,7 @@ public bool IsEnabled(Dictionary<string, string> parameters, UnleashContext cont
                 groupId = "";
             }
 
-            if (!string.IsNullOrEmpty(stickinessId))
+            if (!(stickinessId is null))
             {
                 var normalizedUserId = StrategyUtils.GetNormalizedNumber(stickinessId, groupId, 0);
                 return percentage > 0 && normalizedUserId <= percentage;
diff --git a/tests/Unleash.Tests/Strategy/FlexibleRolloutStrategyTest.cs b/tests/Unleash.Tests/Strategy/FlexibleRolloutStrategyTest.cs
index 8ddd2f2d..3259a545 100644
--- a/tests/Unleash.Tests/Strategy/FlexibleRolloutStrategyTest.cs
+++ b/tests/Unleash.Tests/Strategy/FlexibleRolloutStrategyTest.cs
@@ -337,5 +337,27 @@ public void Should_be_enabled_without_a_context() {
             // Assert
             enabled.Should().BeTrue();
         }
+        
+        [Test]
+        public void Should_be_enabled_for_empty_userid() {
+            // Arrange
+            var strategy = new FlexibleRolloutStrategy();
+            var parameters = new Dictionary<string, string>
+            {
+                { "rollout", "100" },
+                { "stickiness", "default" },
+                { "groupId", "Feature.flexible.rollout.custom.stickiness_100" }
+            };
+            var context = new UnleashContext
+            {
+                UserId = string.Empty
+            };
+
+            // Act
+            var enabled = strategy.IsEnabled(parameters, context);
+
+            // Assert
+            enabled.Should().BeTrue();
+        }
     }
 }