diff --git a/src/vs/workbench/parts/markers/browser/markersFileDecorations.ts b/src/vs/workbench/parts/markers/browser/markersFileDecorations.ts
index 9030dd7375eb78289932e25673fadfafa5cb5ec0..b5dad47b841cad34cecdeb0506d4e20f6c761b31 100644
--- a/src/vs/workbench/parts/markers/browser/markersFileDecorations.ts
+++ b/src/vs/workbench/parts/markers/browser/markersFileDecorations.ts
@@ -44,12 +44,14 @@ class MarkersFileDecorations implements IWorkbenchContribution {
 
 	private _onDidChangeMarker(resources: URI[]): void {
 		for (const resource of resources) {
-			const markers = this._markerService.read({ resource });
+			const markers = this._markerService.read({ resource })
+				.sort((a, b) => Severity.compare(a.severity, b.severity));
+
 			if (!isFalsyOrEmpty(markers)) {
-				const data = markers.map(this._toFileDecorationData, this);
-				this._decorationsService.setFileDecorations(this._type, resource, data);
+				const data = this._toFileDecorationData(markers[0]);
+				this._decorationsService.setFileDecoration(this._type, resource, data);
 			} else {
-				this._decorationsService.unsetFileDecorations(this._type, resource);
+				this._decorationsService.unsetFileDecoration(this._type, resource);
 			}
 		}
 	}
diff --git a/src/vs/workbench/parts/scm/electron-browser/scmFileDecorations.ts b/src/vs/workbench/parts/scm/electron-browser/scmFileDecorations.ts
index 13f3ffb8f8eaa0da99c083f7334a6ec2c79726b9..59509fd3c01aed691a528cf4c40ac6c54a42d192 100644
--- a/src/vs/workbench/parts/scm/electron-browser/scmFileDecorations.ts
+++ b/src/vs/workbench/parts/scm/electron-browser/scmFileDecorations.ts
@@ -49,11 +49,11 @@ export class FileDecorations implements IWorkbenchContribution {
 				for (const resource of group.resourceCollection.resources) {
 					// TODO@Joh have a better color and icon which is based
 					// on the resource decoration
-					this._decorationsService.setFileDecorations(type, resource.sourceUri, [{
+					this._decorationsService.setFileDecoration(type, resource.sourceUri, {
 						severity: Severity.Info,
 						message: resource.decorations.tooltip,
 						color
-					}]);
+					});
 
 					newDecorations.set(resource.sourceUri.toString(), resource.sourceUri);
 				}
@@ -61,7 +61,7 @@ export class FileDecorations implements IWorkbenchContribution {
 
 			oldDecorations.forEach((value, key) => {
 				if (!newDecorations.has(key)) {
-					this._decorationsService.unsetFileDecorations(type, value);
+					this._decorationsService.unsetFileDecoration(type, value);
 				}
 			});
 
diff --git a/src/vs/workbench/services/fileDecorations/browser/fileDecorations.ts b/src/vs/workbench/services/fileDecorations/browser/fileDecorations.ts
index 3bb20dba2233f05f5969d8174beb419f90cbd331..15e1feb21d47c3c7b833e0157297089b88dc4ab7 100644
--- a/src/vs/workbench/services/fileDecorations/browser/fileDecorations.ts
+++ b/src/vs/workbench/services/fileDecorations/browser/fileDecorations.ts
@@ -43,9 +43,9 @@ export interface IFileDecorationsService {
 
 	registerDecorationType(label: string): DecorationType;
 
-	setFileDecorations(type: DecorationType, target: URI, data: IFileDecorationData[]): void;
+	setFileDecoration(type: DecorationType, target: URI, data: IFileDecorationData): void;
 
-	unsetFileDecorations(type: DecorationType, target: URI): void;
+	unsetFileDecoration(type: DecorationType, target: URI): void;
 
 	getDecorations(uri: URI, includeChildren: boolean): IFileDecoration[];
 
diff --git a/src/vs/workbench/services/fileDecorations/browser/fileDecorationsService.ts b/src/vs/workbench/services/fileDecorations/browser/fileDecorationsService.ts
index a7c225ba106979057d255f2d427b9f24a0ec2956..e4f2932b524e8485c720c0392eb8da02320787f2 100644
--- a/src/vs/workbench/services/fileDecorations/browser/fileDecorationsService.ts
+++ b/src/vs/workbench/services/fileDecorations/browser/fileDecorationsService.ts
@@ -9,15 +9,13 @@ import Severity from 'vs/base/common/severity';
 import Event, { Emitter, debounceEvent } from 'vs/base/common/event';
 import { IFileDecorationsService, IFileDecoration, DecorationType, IFileDecorationData } from 'vs/workbench/services/fileDecorations/browser/fileDecorations';
 import { TernarySearchTree } from 'vs/base/common/map';
-import { mergeSort, isFalsyOrEmpty } from 'vs/base/common/arrays';
-
 
 export class FileDecorationsService implements IFileDecorationsService {
 
 	readonly _serviceBrand;
 
 	private readonly _onDidChangeFileDecoration = new Emitter<URI>();
-	private readonly _types = new Map<DecorationType, TernarySearchTree<IFileDecoration[]>>();
+	private readonly _types = new Map<DecorationType, TernarySearchTree<IFileDecoration>>();
 
 	readonly onDidChangeFileDecoration: Event<URI[]> = debounceEvent<URI, URI[]>(
 		this._onDidChangeFileDecoration.event,
@@ -44,17 +42,16 @@ export class FileDecorationsService implements IFileDecorationsService {
 				}
 			}
 		};
-		this._types.set(type, TernarySearchTree.forPaths<IFileDecoration[]>());
+		this._types.set(type, TernarySearchTree.forPaths<IFileDecoration>());
 		return type;
 	}
 
-	setFileDecorations(type: DecorationType, target: URI, data: IFileDecorationData[]): void {
-		let decorations = mergeSort(data.map(data => ({ type, ...data })), FileDecorationsService._compareFileDecorationsBySeverity);
-		this._types.get(type).set(target.toString(), decorations);
+	setFileDecoration(type: DecorationType, target: URI, data: IFileDecorationData): void {
+		this._types.get(type).set(target.toString(), { type, ...data });
 		this._onDidChangeFileDecoration.fire(target);
 	}
 
-	unsetFileDecorations(type: DecorationType, target: URI): void {
+	unsetFileDecoration(type: DecorationType, target: URI): void {
 		this._types.get(type).delete(target.toString());
 		this._onDidChangeFileDecoration.fire(target);
 	}
@@ -76,7 +73,7 @@ export class FileDecorationsService implements IFileDecorationsService {
 			if (!top || FileDecorationsService._compareFileDecorationsBySeverity(top, decoration) > 0) {
 				top = decoration;
 			}
-			return top.severity === Severity.Error;
+			return top !== undefined && top.severity === Severity.Error;
 		});
 		return top;
 	}
@@ -91,13 +88,11 @@ export class FileDecorationsService implements IFileDecorationsService {
 			if (includeChildren) {
 				let newTree = tree.findSuperstr(key);
 				if (newTree) {
-					newTree.forEach(([, data]) => done = done || data.some(callback));
+					newTree.forEach(([, deco]) => done = done || callback(deco));
 				}
 			} else {
-				let list = tree.get(key);
-				if (!isFalsyOrEmpty(list)) {
-					done = list.some(callback);
-				}
+				let deco = tree.get(key);
+				done = done || deco && callback(deco);
 			}
 		});
 	}