diff --git a/src/blur.js b/src/blur.ts
similarity index 88%
rename from src/blur.js
rename to src/blur.ts
index 0f674300..802e9481 100644
--- a/src/blur.js
+++ b/src/blur.ts
@@ -1,6 +1,6 @@
 import {getActiveElement, isFocusable, eventWrapper} from './utils'
 
-function blur(element) {
+function blur(element: Element) {
   if (!isFocusable(element)) return
 
   const wasActive = getActiveElement(element.ownerDocument) === element
diff --git a/src/focus.js b/src/focus.ts
similarity index 88%
rename from src/focus.js
rename to src/focus.ts
index ae1b8c89..7d602a9e 100644
--- a/src/focus.js
+++ b/src/focus.ts
@@ -1,6 +1,6 @@
 import {getActiveElement, isFocusable, eventWrapper} from './utils'
 
-function focus(element) {
+function focus(element: Element) {
   if (!isFocusable(element)) return
 
   const isAlreadyActive = getActiveElement(element.ownerDocument) === element
diff --git a/src/hover.js b/src/hover.ts
similarity index 80%
rename from src/hover.js
rename to src/hover.ts
index b347b90d..12199684 100644
--- a/src/hover.js
+++ b/src/hover.ts
@@ -2,19 +2,20 @@ import {fireEvent} from '@testing-library/dom'
 import {
   isLabelWithInternallyDisabledControl,
   getMouseEventOptions,
+  isDisabled,
 } from './utils'
 
 // includes `element`
-function getParentElements(element) {
+function getParentElements(element: Element) {
   const parentElements = [element]
-  let currentElement = element
+  let currentElement: Element | null = element
   while ((currentElement = currentElement.parentElement) != null) {
     parentElements.push(currentElement)
   }
   return parentElements
 }
 
-function hover(element, init) {
+function hover(element: Element, init?: MouseEventInit) {
   if (isLabelWithInternallyDisabledControl(element)) return
 
   const parentElements = getParentElements(element).reverse()
@@ -23,32 +24,32 @@ function hover(element, init) {
   for (const el of parentElements) {
     fireEvent.pointerEnter(el, init)
   }
-  if (!element.disabled) {
+  if (!isDisabled(element)) {
     fireEvent.mouseOver(element, getMouseEventOptions('mouseover', init))
     for (const el of parentElements) {
       fireEvent.mouseEnter(el, getMouseEventOptions('mouseenter', init))
     }
   }
   fireEvent.pointerMove(element, init)
-  if (!element.disabled) {
+  if (!isDisabled(element)) {
     fireEvent.mouseMove(element, getMouseEventOptions('mousemove', init))
   }
 }
 
-function unhover(element, init) {
+function unhover(element: Element, init?: MouseEventInit) {
   if (isLabelWithInternallyDisabledControl(element)) return
 
   const parentElements = getParentElements(element)
 
   fireEvent.pointerMove(element, init)
-  if (!element.disabled) {
+  if (!isDisabled(element)) {
     fireEvent.mouseMove(element, getMouseEventOptions('mousemove', init))
   }
   fireEvent.pointerOut(element, init)
   for (const el of parentElements) {
     fireEvent.pointerLeave(el, init)
   }
-  if (!element.disabled) {
+  if (!isDisabled(element)) {
     fireEvent.mouseOut(element, getMouseEventOptions('mouseout', init))
     for (const el of parentElements) {
       fireEvent.mouseLeave(el, getMouseEventOptions('mouseleave', init))
diff --git a/src/tab.ts b/src/tab.ts
index 95a11171..5dd123e5 100644
--- a/src/tab.ts
+++ b/src/tab.ts
@@ -143,7 +143,10 @@ function tab({shift = false, focusTrap}: tabOptions = {}) {
 
   if (continueToTab) {
     if (nextElement === document.body) {
-      blur(previousElement)
+      /* istanbul ignore else */
+      if (previousElement) {
+        blur(previousElement)
+      }
     } else {
       focus(nextElement)
     }