diff --git a/src/tilesource.js b/src/tilesource.js
index 3195a90c..2a5225c0 100644
--- a/src/tilesource.js
+++ b/src/tilesource.js
@@ -569,13 +569,13 @@ $.TileSource.prototype = {
     },
 
     /**
-     * Responsible determining if a the particular TileSource supports the
+     * Responsible for determining if the particular TileSource supports the
      * data format ( and allowed to apply logic against the url the data was
      * loaded from, if any ). Overriding implementations are expected to do
      * something smart with data and / or url to determine support.  Also
-     * understand that iteration order of TileSources is not guarunteed so
+     * understand that iteration order of TileSources is not guaranteed so
      * please make sure your data or url is expressive enough to ensure a simple
-     * and sufficient mechanisim for clear determination.
+     * and sufficient mechanism for clear determination.
      * @function
      * @param {String|Object|Array|Document} data
      * @param {String} url - the url the data was loaded
@@ -776,7 +776,7 @@ $.TileSource.prototype = {
         };
 
         // Load the tile with an AJAX request if the loadWithAjax option is
-        // set. Otherwise load the image by setting the source proprety of the image object.
+        // set. Otherwise load the image by setting the source property of the image object.
         if (context.loadWithAjax) {
             dataStore.request = $.makeAjaxRequest({
                 url: context.src,
diff --git a/src/viewer.js b/src/viewer.js
index 037e3016..5431626f 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -2198,7 +2198,7 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
      *      viewport which the location coordinates will be treated as relative
      *      to.
      * @param {function} [onDraw] - If supplied the callback is called when the overlay
-     *      needs to be drawn. It it the responsibility of the callback to do any drawing/positioning.
+     *      needs to be drawn. It is the responsibility of the callback to do any drawing/positioning.
      *      It is passed position, size and element.
      * @returns {OpenSeadragon.Viewer} Chainable.
      * @fires OpenSeadragon.Viewer.event:add-overlay
diff --git a/src/webgldrawer.js b/src/webgldrawer.js
index f0b69d00..d36a7b74 100644
--- a/src/webgldrawer.js
+++ b/src/webgldrawer.js
@@ -351,7 +351,7 @@
                         // This can apparently happen on some systems if too many WebGL contexts have been created
                         // in which case maxTextures can be null, leading to out of bounds errors with the array.
                         // For example, when viewers were created and not destroyed in the test suite, this error
-                        // occured in the TravisCI tests, though it did not happen when testing locally either in
+                        // occurred in the TravisCI tests, though it did not happen when testing locally either in
                         // a browser or on the command line via grunt test.
 
                         throw(new Error(`WegGL error: bad value for gl parameter MAX_TEXTURE_IMAGE_UNITS (${maxTextures}). This could happen
diff --git a/test/modules/iiif.js b/test/modules/iiif.js
index e64e34a9..28480766 100644
--- a/test/modules/iiif.js
+++ b/test/modules/iiif.js
@@ -243,7 +243,7 @@
         /*
          * FIXME: following https://iiif.io/api/image/3.0/#47-canonical-uri-syntax and
          * https://iiif.io/api/image/2.1/#canonical-uri-syntax, I'd expect 'max' to be required to
-         * be served by a level 0 compliant service instead of 'w,h', 'full' instead of 'w,' respectivley.
+         * be served by a level 0 compliant service instead of 'w,h', 'full' instead of 'w,' respectively.
          */
         //assert.equal(levelsVersion3[1].url, 'http://example.com/identifier/full/max/0/default.jpg');
     });