diff --git a/.changeset/hot-walls-share.md b/.changeset/hot-walls-share.md
new file mode 100644
index 00000000..441ef7ce
--- /dev/null
+++ b/.changeset/hot-walls-share.md
@@ -0,0 +1,5 @@
+---
+"@effect/language-service": patch
+---
+
+Fix the class self mismatch diagnostic so it also reports invalid `ServiceMap.Service` self type parameters.
diff --git a/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.classSelfMismatch_fix.from317to328.output b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.classSelfMismatch_fix.from317to328.output
new file mode 100644
index 00000000..1b6e3134
--- /dev/null
+++ b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.classSelfMismatch_fix.from317to328.output
@@ -0,0 +1,12 @@
+// code fix classSelfMismatch_fix  output for range 317 - 328
+import { ServiceMap, Effect } from "effect"
+
+export class CorrectName extends ServiceMap.Service<CorrectName, {
+    writeCache: () => Effect.Effect<void, never, FileSystem | Cache>
+    readCache: Effect.Effect<void, never, FileSystem | Cache>
+}>()("CorrectName") {}
+
+export class WrongName extends ServiceMap.Service<WrongName, {
+    writeCache: () => Effect.Effect<void, never, FileSystem | Cache>
+    readCache: Effect.Effect<void, never, FileSystem | Cache>
+}>()("WrongName") {}
diff --git a/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.codefixes b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.codefixes
new file mode 100644
index 00000000..5703d556
--- /dev/null
+++ b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.codefixes
@@ -0,0 +1,3 @@
+classSelfMismatch_fix from 317 to 328
+classSelfMismatch_skipNextLine from 317 to 328
+classSelfMismatch_skipFile from 317 to 328
\ No newline at end of file
diff --git a/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.output b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.output
new file mode 100644
index 00000000..3965451c
--- /dev/null
+++ b/packages/harness-effect-v4/__snapshots__/diagnostics/classSelfMismatch_service.ts.output
@@ -0,0 +1,2 @@
+CorrectName
+8:50 - 8:61 | 1 | Self type parameter should be 'WrongName'    effect(classSelfMismatch)
\ No newline at end of file
diff --git a/packages/harness-effect-v4/examples/diagnostics/classSelfMismatch_service.ts b/packages/harness-effect-v4/examples/diagnostics/classSelfMismatch_service.ts
new file mode 100644
index 00000000..8b834e89
--- /dev/null
+++ b/packages/harness-effect-v4/examples/diagnostics/classSelfMismatch_service.ts
@@ -0,0 +1,11 @@
+import { ServiceMap, Effect } from "effect"
+
+export class CorrectName extends ServiceMap.Service<CorrectName, {
+    writeCache: () => Effect.Effect<void, never, FileSystem | Cache>
+    readCache: Effect.Effect<void, never, FileSystem | Cache>
+}>()("CorrectName") {}
+
+export class WrongName extends ServiceMap.Service<CorrectName, {
+    writeCache: () => Effect.Effect<void, never, FileSystem | Cache>
+    readCache: Effect.Effect<void, never, FileSystem | Cache>
+}>()("WrongName") {}
diff --git a/packages/language-service/src/diagnostics/classSelfMismatch.ts b/packages/language-service/src/diagnostics/classSelfMismatch.ts
index 29e02475..5e3c91fa 100644
--- a/packages/language-service/src/diagnostics/classSelfMismatch.ts
+++ b/packages/language-service/src/diagnostics/classSelfMismatch.ts
@@ -32,6 +32,7 @@ export const classSelfMismatch = LSP.createDiagnostic({
         // Check if this class extends a class that has a Self type parameter
         const result = yield* pipe(
           typeParser.extendsEffectService(node),
+          Nano.orElse(() => typeParser.extendsServiceMapService(node)),
           Nano.orElse(() => typeParser.extendsContextTag(node)),
           Nano.orElse(() => typeParser.extendsEffectTag(node)),
           Nano.orElse(() => typeParser.extendsSchemaClass(node)),