diff --git a/src/validate/html/index.ts b/src/validate/html/index.ts
index ed4eaf4d38..eabe9d8872 100644
--- a/src/validate/html/index.ts
+++ b/src/validate/html/index.ts
@@ -14,7 +14,7 @@ function isEmptyBlock(node: Node) {
 	if (!/Block$/.test(node.type) || !node.children) return false;
 	if (node.children.length > 1) return false;
 	const child = node.children[0];
-	return !child || (child.type === 'Text' && !/\S/.test(child.data));
+	return !child || (child.type === 'Text' && !/[^ \r\n\f\v\t]/.test(child.data));
 }
 
 export default function validateHtml(validator: Validator, html: Node) {
diff --git a/test/validator/samples/non-empty-block-dev/_config.js b/test/validator/samples/non-empty-block-dev/_config.js
new file mode 100644
index 0000000000..e26996239d
--- /dev/null
+++ b/test/validator/samples/non-empty-block-dev/_config.js
@@ -0,0 +1,3 @@
+export default {
+	dev: true
+};
\ No newline at end of file
diff --git a/test/validator/samples/non-empty-block-dev/input.html b/test/validator/samples/non-empty-block-dev/input.html
new file mode 100644
index 0000000000..ed4b9e6274
--- /dev/null
+++ b/test/validator/samples/non-empty-block-dev/input.html
@@ -0,0 +1,3 @@
+{#if x}
+	 
+{/if}
\ No newline at end of file
diff --git a/test/validator/samples/non-empty-block-dev/warnings.json b/test/validator/samples/non-empty-block-dev/warnings.json
new file mode 100644
index 0000000000..0637a088a0
--- /dev/null
+++ b/test/validator/samples/non-empty-block-dev/warnings.json
@@ -0,0 +1 @@
+[]
\ No newline at end of file