diff --git a/src/parsers/abstract-ast.parser.ts b/src/parsers/abstract-ast.parser.ts
index 7e30562..1e62d49 100644
--- a/src/parsers/abstract-ast.parser.ts
+++ b/src/parsers/abstract-ast.parser.ts
@@ -35,11 +35,7 @@ export abstract class AbstractAstParser {
 	/**
 	 * Find all child nodes of a kind
 	 */
-	protected _findNodes(node: ts.Node, kind: ts.SyntaxKind, onlyOne: boolean = false): ts.Node[] {
-		if (node.kind === kind && onlyOne) {
-			return [node];
-		}
-
+	protected _findNodes(node: ts.Node, kind: ts.SyntaxKind): ts.Node[] {
 		const childrenNodes: ts.Node[] = node.getChildren(this._sourceFile);
 		const initialValue: ts.Node[] = node.kind === kind ? [node] : [];
 
diff --git a/src/parsers/service.parser.ts b/src/parsers/service.parser.ts
index ec2898d..a6f3450 100644
--- a/src/parsers/service.parser.ts
+++ b/src/parsers/service.parser.ts
@@ -9,18 +9,22 @@ export class ServiceParser extends AbstractAstParser implements ParserInterface
 	protected _sourceFile: ts.SourceFile;
 
 	public extract(contents: string, path?: string): TranslationCollection {
-		this._sourceFile = this._createSourceFile(path, contents);
-
 		let collection: TranslationCollection = new TranslationCollection();
 
-		const constructorNodes: ts.ConstructorDeclaration[] = this._findConstructorNodes();
-		constructorNodes.forEach(constructorNode => {
-			const propertyName: string = this._getPropertyName(constructorNode);
+		this._sourceFile = this._createSourceFile(path, contents);
+		const classNodes = this._findClassNodes(this._sourceFile);
+		classNodes.forEach(classNode => {
+			const constructorNode = this._findConstructorNode(classNode);
+			if (!constructorNode) {
+				return;
+			}
+
+			const propertyName: string = this._findTranslateServicePropertyName(constructorNode);
 			if (!propertyName) {
 				return;
 			}
 
-			const callNodes = this._findCallNodes(this._sourceFile, propertyName);
+			const callNodes = this._findCallNodes(classNode, propertyName);
 			callNodes.forEach(callNode => {
 				const keys: string[] = this._getCallArgStrings(callNode);
 				if (keys && keys.length) {
@@ -34,9 +38,9 @@ export class ServiceParser extends AbstractAstParser implements ParserInterface
 
 	/**
 	 * Detect what the TranslateService instance property
-	 * is called by inspecting constructor params
+	 * is called by inspecting constructor arguments
 	 */
-	protected _getPropertyName(constructorNode: ts.ConstructorDeclaration): string {
+	protected _findTranslateServicePropertyName(constructorNode: ts.ConstructorDeclaration): string {
 		if (!constructorNode) {
 			return null;
 		}
@@ -71,12 +75,19 @@ export class ServiceParser extends AbstractAstParser implements ParserInterface
 	}
 
 	/**
-	 * Find constructor nodes
+	 * Find class nodes
 	 */
-	protected _findConstructorNodes(): ts.ConstructorDeclaration[] {
-		const constructors = this._findNodes(this._sourceFile, ts.SyntaxKind.Constructor, true) as ts.ConstructorDeclaration[];
-		if (constructors.length) {
-			return constructors;
+	protected _findClassNodes(node: ts.Node): ts.ClassDeclaration[] {
+		return this._findNodes(node, ts.SyntaxKind.ClassDeclaration) as ts.ClassDeclaration[];
+	}
+
+	/**
+	 * Find constructor
+	 */
+	protected _findConstructorNode(node: ts.ClassDeclaration): ts.ConstructorDeclaration {
+		const constructorNodes = this._findNodes(node, ts.SyntaxKind.Constructor) as ts.ConstructorDeclaration[];
+		if (constructorNodes) {
+			return constructorNodes[0];
 		}
 	}
 
diff --git a/tests/parsers/service.parser.spec.ts b/tests/parsers/service.parser.spec.ts
index 2f134f8..032337f 100644
--- a/tests/parsers/service.parser.spec.ts
+++ b/tests/parsers/service.parser.spec.ts
@@ -170,19 +170,32 @@ describe('ServiceParser', () => {
 			import { TranslateService } from '@ngx-translate/core';
 			export class Stuff {
 				thing: string;
+				translate: any;
 				constructor(thing: string) {
+					this.translate.get('Not me');
 					this.thing = thing;
 				}
 			}
 			@Injectable()
+			export class MyComponent {
+				constructor(public translate: TranslateService) {
+					this.translate.instant("Extract me!");
+				}
+			}
+			export class OtherClass {
+				constructor(thing: string, _translate: TranslateService) {
+					this._translate.get("Do not extract me");
+				}
+			}
+			@Injectable()
 			export class AuthService {
 				constructor(public translate: TranslateService) {
-					console.log(this.translate.instant("Hello!"));
+					this.translate.instant("Hello!");
 				}
 			}
 		`;
 		const keys = parser.extract(contents, componentFilename).keys();
-		expect(keys).to.deep.equal(['Hello!']);
+		expect(keys).to.deep.equal(['Extract me!', 'Hello!']);
 	});
 
 });