diff --git a/lib/checks/label/alt-space-value.js b/lib/checks/label/alt-space-value.js
new file mode 100644
index 0000000000..67fd2b6d66
--- /dev/null
+++ b/lib/checks/label/alt-space-value.js
@@ -0,0 +1,2 @@
+const validAttrValue = /^\s+$/.test(node.getAttribute('alt'));
+return node.hasAttribute('alt') && validAttrValue;
diff --git a/lib/checks/label/alt-space-value.json b/lib/checks/label/alt-space-value.json
new file mode 100644
index 0000000000..11813fe00b
--- /dev/null
+++ b/lib/checks/label/alt-space-value.json
@@ -0,0 +1,11 @@
+{
+	"id": "alt-space-value",
+	"evaluate": "alt-space-value.js",
+	"metadata": {
+		"impact": "critical",
+		"messages": {
+			"pass": "Element has a valid alt attribute value",
+			"fail": "Element has an alt attribute containing only a space character, which is not ignored by all screen readers"
+		}
+	}
+}
diff --git a/lib/rules/image-alt.json b/lib/rules/image-alt.json
index 6d688ee105..1b4791e31d 100644
--- a/lib/rules/image-alt.json
+++ b/lib/rules/image-alt.json
@@ -21,5 +21,5 @@
 		"role-presentation",
 		"role-none"
 	],
-	"none": []
+	"none": ["alt-space-value"]
 }
diff --git a/lib/rules/landmark-complementary-is-top-level.json b/lib/rules/landmark-complementary-is-top-level.json
index c06f1347e1..dac1e93e93 100644
--- a/lib/rules/landmark-complementary-is-top-level.json
+++ b/lib/rules/landmark-complementary-is-top-level.json
@@ -1,17 +1,12 @@
 {
-  "id": "landmark-complementary-is-top-level",
-  "selector": "aside:not([role]), [role=complementary]",
-  "tags": [
-    "cat.semantics",
-    "best-practice"
-  ],
-  "metadata": {
-    "description": "Ensures the complementary landmark or aside is at top level",
-    "help": "Aside must not be contained in another landmark"
-  },
-  "all": [],
-  "any": [
-    "landmark-is-top-level"
-  ],
-  "none": []
+	"id": "landmark-complementary-is-top-level",
+	"selector": "aside:not([role]), [role=complementary]",
+	"tags": ["cat.semantics", "best-practice"],
+	"metadata": {
+		"description": "Ensures the complementary landmark or aside is at top level",
+		"help": "Aside must not be contained in another landmark"
+	},
+	"all": [],
+	"any": ["landmark-is-top-level"],
+	"none": []
 }
diff --git a/test/checks/label/alt-space-value.js b/test/checks/label/alt-space-value.js
new file mode 100644
index 0000000000..ff73233cb8
--- /dev/null
+++ b/test/checks/label/alt-space-value.js
@@ -0,0 +1,31 @@
+describe('alt-space-value', function() {
+	'use strict';
+
+	var checkSetup = axe.testUtils.checkSetup;
+	var checkContext = axe.testUtils.MockCheckContext();
+	var check = checks['alt-space-value'];
+
+	afterEach(function() {
+		checkContext.reset();
+	});
+
+	it('should return true if alt contains a space character', function() {
+		var params = checkSetup('<img id="target" alt=" " />');
+		assert.isTrue(check.evaluate.apply(checkContext, params));
+	});
+
+	it('should return true if alt contains a non-breaking space character', function() {
+		var params = checkSetup('<img id="target" alt="&nbsp;" />');
+		assert.isTrue(check.evaluate.apply(checkContext, params));
+	});
+
+	it('should return false if alt attribute is empty', function() {
+		var params = checkSetup('<img id="target" alt="" />');
+		assert.isFalse(check.evaluate.apply(checkContext, params));
+	});
+
+	it('should return false if alt attribute has a proper text value', function() {
+		var params = checkSetup('<img id="target" alt="text content" />');
+		assert.isFalse(check.evaluate.apply(checkContext, params));
+	});
+});
diff --git a/test/integration/rules/image-alt/image-alt.html b/test/integration/rules/image-alt/image-alt.html
index 14672b4b0d..3b49f6062f 100644
--- a/test/integration/rules/image-alt/image-alt.html
+++ b/test/integration/rules/image-alt/image-alt.html
@@ -15,5 +15,6 @@
 <img src="img.jpg" id="pass7" role="none">
 <img src="img.jpg" id="pass8" aria-labelledby="ninjamonkeys">
 <div role="img" alt="blah" id="violation6"></div>
+<img src="img.jpg" id="violation7" alt=" " />
 <div role="img" aria-label="blah" id="pass9"></div>
 <svg role="img" id="ignore1"><title>SVG Title</title></svg>
diff --git a/test/integration/rules/image-alt/image-alt.json b/test/integration/rules/image-alt/image-alt.json
index 088b528db5..8fe3368f91 100644
--- a/test/integration/rules/image-alt/image-alt.json
+++ b/test/integration/rules/image-alt/image-alt.json
@@ -7,7 +7,8 @@
 		["#violation3"],
 		["#violation4"],
 		["#violation5"],
-		["#violation6"]
+		["#violation6"],
+		["#violation7"]
 	],
 	"passes": [
 		["#pass1"],