diff --git a/src/vs/workbench/api/node/extHostDiagnostics.ts b/src/vs/workbench/api/node/extHostDiagnostics.ts
index dab90f9e538..d73f73a8dea 100644
--- a/src/vs/workbench/api/node/extHostDiagnostics.ts
+++ b/src/vs/workbench/api/node/extHostDiagnostics.ts
@@ -10,6 +10,7 @@ import URI from 'vs/base/common/uri';
 import Severity from 'vs/base/common/severity';
 import * as vscode from 'vscode';
 import {MainContext, MainThreadDiagnosticsShape, ExtHostDiagnosticsShape} from './extHost.protocol';
+import {Diagnostic} from './extHostTypes';
 
 export class DiagnosticCollection implements vscode.DiagnosticCollection {
 
@@ -98,9 +99,14 @@ export class DiagnosticCollection implements vscode.DiagnosticCollection {
 				// no more than 250 diagnostics per file
 				if (diagnostics.length > DiagnosticCollection._maxDiagnosticsPerFile) {
 					console.warn('diagnostics for %s will be capped to %d (actually is %d)', uri.toString(), DiagnosticCollection._maxDiagnosticsPerFile, diagnostics.length);
-					diagnostics = diagnostics.slice(0, DiagnosticCollection._maxDiagnosticsPerFile);
+					marker = [];
+					const sorted = diagnostics.slice(0).sort(Diagnostic.compare);
+					for (let i = 0; i < DiagnosticCollection._maxDiagnosticsPerFile; i++) {
+						marker.push(DiagnosticCollection._toMarkerData(sorted[i]));
+					}
+				} else {
+					marker = diagnostics.map(DiagnosticCollection._toMarkerData);
 				}
-				marker = diagnostics.map(DiagnosticCollection._toMarkerData);
 			}
 
 			entries.push([<URI> uri, marker]);
diff --git a/src/vs/workbench/api/node/extHostTypes.ts b/src/vs/workbench/api/node/extHostTypes.ts
index c0058a88efd..6a96eff46ce 100644
--- a/src/vs/workbench/api/node/extHostTypes.ts
+++ b/src/vs/workbench/api/node/extHostTypes.ts
@@ -552,6 +552,17 @@ export class Diagnostic {
 			code: this.code,
 		};
 	}
+
+	static compare(a: vscode.Diagnostic, b: vscode.Diagnostic): number{
+		let ret = a.severity - b.severity;
+		if (ret === 0) {
+			ret = a.range.start.compareTo(b.range.start);
+		}
+		if (ret === 0) {
+			ret = a.message.localeCompare(b.message);
+		}
+		return ret;
+	}
 }
 
 export class Hover {
diff --git a/src/vs/workbench/test/node/api/extHostDiagnostics.test.ts b/src/vs/workbench/test/node/api/extHostDiagnostics.test.ts
index ab1dd37b041..2f4e21e89ea 100644
--- a/src/vs/workbench/test/node/api/extHostDiagnostics.test.ts
+++ b/src/vs/workbench/test/node/api/extHostDiagnostics.test.ts
@@ -7,8 +7,9 @@
 
 import * as assert from 'assert';
 import URI from 'vs/base/common/uri';
+import Severity from 'vs/base/common/severity';
 import {DiagnosticCollection} from 'vs/workbench/api/node/extHostDiagnostics';
-import {Diagnostic, Range} from 'vs/workbench/api/node/extHostTypes';
+import {Diagnostic, DiagnosticSeverity, Range} from 'vs/workbench/api/node/extHostTypes';
 import {MainThreadDiagnosticsShape} from 'vs/workbench/api/node/extHost.protocol';
 import {TPromise} from 'vs/base/common/winjs.base';
 import {IMarkerData} from 'vs/platform/markers/common/markers';
@@ -170,9 +171,18 @@ suite('ExtHostDiagnostics', () => {
 		});
 		let uri = URI.parse('aa:bb');
 
-		collection.set(uri, new Array(500).map((value, i) => new Diagnostic(new Range(i, 0, i + 1, 0), `error#${i}`)));
+		let diagnostics: Diagnostic[] = [];
+		for (let i = 0; i < 500; i++) {
+			diagnostics.push(new Diagnostic(new Range(i, 0, i + 1, 0), `error#${i}`, i < 300
+				? DiagnosticSeverity.Warning
+				: DiagnosticSeverity.Error));
+		}
+
+		collection.set(uri, diagnostics);
 		assert.equal(collection.get(uri).length, 500);
 		assert.equal(lastEntries.length, 1);
 		assert.equal(lastEntries[0][1].length, 250);
+		assert.equal(lastEntries[0][1][0].severity, Severity.Error);
+		assert.equal(lastEntries[0][1][200].severity, Severity.Warning);
 	});
 });
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