diff --git a/cms/static/coffee/spec/models/settings_course_grader_spec.coffee b/cms/static/coffee/spec/models/settings_course_grader_spec.coffee
index ed43b5d036..3007c5377f 100644
--- a/cms/static/coffee/spec/models/settings_course_grader_spec.coffee
+++ b/cms/static/coffee/spec/models/settings_course_grader_spec.coffee
@@ -23,5 +23,13 @@ define ["js/models/settings/course_grader"], (CourseGrader) ->
                 model = new CourseGrader()
                 errors = model.validate({min_count: 0, drop_count: ''}, {validate:true})
                 expect(errors.min_count).toBe('Please enter an integer greater than 0.')
-                expect(errors.drop_count).toBe('Please enter an integer.')
+                expect(errors.drop_count).toBe('Please enter non-negative integer.')
+                # don't allow negative integers
+                errors = model.validate({min_count: -12, drop_count: -1}, {validate:true})
+                expect(errors.min_count).toBe('Please enter an integer greater than 0.')
+                expect(errors.drop_count).toBe('Please enter non-negative integer.')
+                # don't allow floats
+                errors = model.validate({min_count: 12.2, drop_count: 1.5}, {validate:true})
+                expect(errors.min_count).toBe('Please enter an integer greater than 0.')
+                expect(errors.drop_count).toBe('Please enter non-negative integer.')
 
diff --git a/cms/static/js/models/settings/course_grader.js b/cms/static/js/models/settings/course_grader.js
index 6f46af5f02..0fee8f6555 100644
--- a/cms/static/js/models/settings/course_grader.js
+++ b/cms/static/js/models/settings/course_grader.js
@@ -51,19 +51,19 @@ var CourseGrader = Backbone.Model.extend({
             }}
         if (_.has(attrs, 'min_count')) {
             var intMinCount = parseInt(attrs.min_count, 10);
-            if (!isFinite(intMinCount) || /\D+/.test(intMinCount) || intMinCount < 1) {
+            if (!isFinite(intMinCount) || /\D+/.test(attrs.min_count) || intMinCount < 1) {
                 errors.min_count = gettext("Please enter an integer greater than 0.");
             }
             else attrs.min_count = intMinCount;
         }
         if (_.has(attrs, 'drop_count')) {
             var intDropCount = parseInt(attrs.drop_count, 10);
-            if (!isFinite(intDropCount) || /\D+/.test(intDropCount) || isNaN(intDropCount)) {
-                errors.drop_count = gettext("Please enter an integer.");
+            if (!isFinite(intDropCount) || /\D+/.test(attrs.drop_count) || isNaN(intDropCount) || intDropCount < 0) {
+                errors.drop_count = gettext("Please enter non-negative integer.");
             }
             else attrs.drop_count = intDropCount;
         }
-        if (_.has(attrs, 'min_count') && _.has(attrs, 'drop_count') && attrs.drop_count > attrs.min_count) {
+        if (_.has(attrs, 'min_count') && _.has(attrs, 'drop_count') && !_.has(errors, 'min_count') && !_.has(errors, 'drop_count') && attrs.drop_count > attrs.min_count) {
             errors.drop_count = _.template(
                 gettext("Cannot drop more <% attrs.types %> than will assigned."),
                 attrs, {variable: 'attrs'});