diff --git a/src/OpenFeature/Providers/Memory/InMemoryProvider.cs b/src/OpenFeature/Providers/Memory/InMemoryProvider.cs
index f95a0a06a..2eec879d0 100644
--- a/src/OpenFeature/Providers/Memory/InMemoryProvider.cs
+++ b/src/OpenFeature/Providers/Memory/InMemoryProvider.cs
@@ -3,7 +3,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using OpenFeature.Constant;
-using OpenFeature.Error;
 using OpenFeature.Model;
 
 namespace OpenFeature.Providers.Memory
@@ -112,7 +111,7 @@ private ResolutionDetails<T> Resolve<T>(string flagKey, T defaultValue, Evaluati
                 return value.Evaluate(flagKey, defaultValue, context);
             }
 
-            throw new TypeMismatchException($"flag {flagKey} is not of type {typeof(T)}");
+            return new ResolutionDetails<T>(flagKey, defaultValue, ErrorType.TypeMismatch, Reason.Error);
         }
     }
 }
diff --git a/test/OpenFeature.Tests/Providers/Memory/InMemoryProviderTests.cs b/test/OpenFeature.Tests/Providers/Memory/InMemoryProviderTests.cs
index 7a174fc51..c575dc56c 100644
--- a/test/OpenFeature.Tests/Providers/Memory/InMemoryProviderTests.cs
+++ b/test/OpenFeature.Tests/Providers/Memory/InMemoryProviderTests.cs
@@ -186,9 +186,14 @@ public async Task MissingFlag_ShouldReturnFlagNotFoundEvaluationFlag()
         }
 
         [Fact]
-        public async Task MismatchedFlag_ShouldThrow()
+        public async Task MismatchedFlag_ShouldReturnTypeMismatchError()
         {
-            await Assert.ThrowsAsync<TypeMismatchException>(() => this.commonProvider.ResolveStringValueAsync("boolean-flag", "nope", EvaluationContext.Empty));
+            // Act
+            var result = await this.commonProvider.ResolveStringValueAsync("boolean-flag", "nope", EvaluationContext.Empty);
+
+            // Assert
+            Assert.Equal(Reason.Error, result.Reason);
+            Assert.Equal(ErrorType.TypeMismatch, result.ErrorType);
         }
 
         [Fact]