diff --git a/src/lib/ThumbnailsSidebar.js b/src/lib/ThumbnailsSidebar.js
index 7800156d01..72e1bde4c5 100644
--- a/src/lib/ThumbnailsSidebar.js
+++ b/src/lib/ThumbnailsSidebar.js
@@ -265,13 +265,11 @@ class ThumbnailsSidebar {
      */
     setCurrentPage(pageNumber) {
         const parsedPageNumber = parseInt(pageNumber, 10);
-        if (!parsedPageNumber || parsedPageNumber < 1 || parsedPageNumber > this.pdfViewer.pagesCount) {
-            return;
-        }
 
-        this.currentPage = parsedPageNumber;
-
-        this.applyCurrentPageSelection();
+        if (parsedPageNumber >= 1 && parsedPageNumber <= this.pdfViewer.pagesCount) {
+            this.currentPage = parsedPageNumber;
+            this.applyCurrentPageSelection();
+        }
     }
 
     /**
diff --git a/src/lib/__tests__/ThumbnailsSidebar-test.js b/src/lib/__tests__/ThumbnailsSidebar-test.js
index 48b515a1c5..f712f0df03 100644
--- a/src/lib/__tests__/ThumbnailsSidebar-test.js
+++ b/src/lib/__tests__/ThumbnailsSidebar-test.js
@@ -221,4 +221,117 @@ describe('ThumbnailsSidebar', () => {
             });
         });
     });
+
+    describe('thumbnailClickHandler()', () => {
+        let targetEl;
+        let evt;
+
+        beforeEach(() => {
+            stubs.onClickHandler = sandbox.stub();
+            stubs.preventDefault = sandbox.stub();
+            stubs.stopImmediatePropagation = sandbox.stub();
+
+            targetEl = document.createElement('div');
+            targetEl.classList.add('bp-thumbnail');
+            targetEl.dataset.bpPageNum = '3';
+
+            evt = {
+                target: targetEl,
+                preventDefault: stubs.preventDefault,
+                stopImmediatePropagation: stubs.stopImmediatePropagation
+            };
+
+            thumbnailsSidebar.onClickHandler = stubs.onClickHandler;
+        });
+
+        it('should call the onClickHandler if target is a thumbnail element', () => {
+            thumbnailsSidebar.thumbnailClickHandler(evt);
+
+            expect(stubs.onClickHandler).to.be.calledWith(3);
+            expect(stubs.preventDefault).to.be.called;
+            expect(stubs.stopImmediatePropagation).to.be.called;
+        });
+
+        it('should not call the onClickHandler if target is not thumbnail element', () => {
+            targetEl.classList.remove('bp-thumbnail');
+            thumbnailsSidebar.thumbnailClickHandler(evt);
+
+            expect(stubs.onClickHandler).not.to.be.called;
+            expect(stubs.preventDefault).to.be.called;
+            expect(stubs.stopImmediatePropagation).to.be.called;
+        });
+    });
+
+    describe('setCurrentPage()', () => {
+        beforeEach(() => {
+            stubs.applyCurrentPageSelection = sandbox.stub(thumbnailsSidebar, 'applyCurrentPageSelection');
+            thumbnailsSidebar.pdfViewer = { pagesCount: 10 };
+        });
+
+        const paramaterizedTests = [
+            { name: 'pageNumber is undefined', pageNumber: undefined },
+            { name: 'pageNumber is less than 1', pageNumber: 0 },
+            { name: 'pageNumber is greater than last page', pageNumber: 11 }
+        ];
+
+        paramaterizedTests.forEach(({ name, pageNumber }) => {
+            it(`should do nothing if ${name}`, () => {
+                thumbnailsSidebar.setCurrentPage(pageNumber);
+
+                expect(thumbnailsSidebar.currentPage).to.be.undefined;
+                expect(stubs.applyCurrentPageSelection).not.to.be.called;
+            });
+        });
+
+        it('should set the currentPage and apply current page selection', () => {
+            thumbnailsSidebar.setCurrentPage(3);
+
+            expect(thumbnailsSidebar.currentPage).to.be.equal(3);
+            expect(stubs.applyCurrentPageSelection).to.be.called;
+        });
+    });
+
+    describe('applyCurrentPageSelection()', () => {
+        let thumbnails;
+
+        beforeEach(() => {
+            stubs.addClass = sandbox.stub();
+            stubs.removeClass = sandbox.stub();
+
+            // eslint-disable-next-line
+            const createTestThumbnail = (pageNum) => {
+                const thumbnail = document.createElement('div');
+                thumbnail.dataset.bpPageNum = pageNum;
+                thumbnail.classList.add = stubs.addClass;
+                thumbnail.classList.remove = stubs.removeClass;
+                return thumbnail;
+            };
+
+            const thumbnail1 = createTestThumbnail('1');
+            const thumbnail2 = createTestThumbnail('2');
+            const thumbnail3 = createTestThumbnail('3');
+
+            thumbnails = [thumbnail1, thumbnail2, thumbnail3];
+
+            thumbnailsSidebar.currentThumbnails = thumbnails;
+        });
+
+        it('should remove the is selected class from all thumbnails', () => {
+            thumbnailsSidebar.currentPage = 10;
+
+            thumbnailsSidebar.applyCurrentPageSelection();
+
+            expect(stubs.removeClass).to.be.calledThrice;
+            expect(stubs.addClass).not.to.be.called;
+        });
+
+        it('should remove the is selected class from all thumbnails', () => {
+            thumbnailsSidebar.currentPage = 2;
+
+            thumbnailsSidebar.applyCurrentPageSelection();
+
+            expect(stubs.removeClass).to.be.calledTwice;
+            expect(stubs.addClass).to.be.calledOnce;
+        });
+    });
 });