diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3fceb5f2fc..459cf656c7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,9 @@
 
 ## Unreleased
 
+* Fix misaligned line numbers in source maps ([#3906](https://github.com/sveltejs/svelte/issues/3906))
 * Fix reactivity with imported values that are then mutated ([#4555](https://github.com/sveltejs/svelte/issues/4555))
+* Display a11y warning for `href="javascript:..."` ([#4733](https://github.com/sveltejs/svelte/pull/4733))
 
 ## 3.21.0
 
diff --git a/src/compiler/compile/nodes/Element.ts b/src/compiler/compile/nodes/Element.ts
index c2f7c20c68..f7f3cc55bc 100644
--- a/src/compiler/compile/nodes/Element.ts
+++ b/src/compiler/compile/nodes/Element.ts
@@ -430,7 +430,7 @@ export default class Element extends Node {
 			if (href_attribute) {
 				const href_value = href_attribute.get_static_value();
 				
-				if (href_value === '' || href_value === '#') {
+				if (href_value === '' || href_value === '#' || /^\W*javascript:/i.test(href_value)) {
 					component.warn(href_attribute, {
 						code: `a11y-invalid-attribute`,
 						message: `A11y: '${href_value}' is not a valid ${href_attribute.name} attribute`
diff --git a/src/compiler/parse/read/script.ts b/src/compiler/parse/read/script.ts
index 130c346ba1..8260894215 100644
--- a/src/compiler/parse/read/script.ts
+++ b/src/compiler/parse/read/script.ts
@@ -37,7 +37,8 @@ export default function read_script(parser: Parser, start: number, attributes: N
 		message: `<script> must have a closing tag`
 	});
 
-	const source = ' '.repeat(script_start) + parser.template.slice(script_start, script_end);
+	const source = parser.template.slice(0, script_start).replace(/[^\n]/g, ' ') +
+		parser.template.slice(script_start, script_end);
 	parser.index = script_end + script_closing_tag.length;
 
 	let ast: Program;
diff --git a/test/sourcemaps/samples/script-after-comment/input.svelte b/test/sourcemaps/samples/script-after-comment/input.svelte
new file mode 100644
index 0000000000..1f06455678
--- /dev/null
+++ b/test/sourcemaps/samples/script-after-comment/input.svelte
@@ -0,0 +1,9 @@
+<!--
+	Multiline
+	comment
+-->
+<script>
+	function assertThisLine() {}
+</script>
+
+{foo.bar.baz}
diff --git a/test/sourcemaps/samples/script-after-comment/test.js b/test/sourcemaps/samples/script-after-comment/test.js
new file mode 100644
index 0000000000..b473970112
--- /dev/null
+++ b/test/sourcemaps/samples/script-after-comment/test.js
@@ -0,0 +1,16 @@
+export function test({ assert, smc, locateInSource, locateInGenerated }) {
+	const expected = locateInSource( 'assertThisLine' );
+	const start = locateInGenerated( 'assertThisLine' );
+
+	const actual = smc.originalPositionFor({
+		line: start.line + 1,
+		column: start.column
+	});
+
+	assert.deepEqual( actual, {
+		source: 'input.svelte',
+		name: null,
+		line: expected.line + 1,
+		column: expected.column
+	});
+}
diff --git a/test/sourcemaps/samples/two-scripts/input.svelte b/test/sourcemaps/samples/two-scripts/input.svelte
new file mode 100644
index 0000000000..4c869827c0
--- /dev/null
+++ b/test/sourcemaps/samples/two-scripts/input.svelte
@@ -0,0 +1,9 @@
+<script context="module">
+	export let first;
+</script>
+
+<script>
+	function assertThisLine() {}
+</script>
+
+{foo.bar.baz}
diff --git a/test/sourcemaps/samples/two-scripts/test.js b/test/sourcemaps/samples/two-scripts/test.js
new file mode 100644
index 0000000000..b473970112
--- /dev/null
+++ b/test/sourcemaps/samples/two-scripts/test.js
@@ -0,0 +1,16 @@
+export function test({ assert, smc, locateInSource, locateInGenerated }) {
+	const expected = locateInSource( 'assertThisLine' );
+	const start = locateInGenerated( 'assertThisLine' );
+
+	const actual = smc.originalPositionFor({
+		line: start.line + 1,
+		column: start.column
+	});
+
+	assert.deepEqual( actual, {
+		source: 'input.svelte',
+		name: null,
+		line: expected.line + 1,
+		column: expected.column
+	});
+}
diff --git a/test/validator/samples/a11y-anchor-is-valid/input.svelte b/test/validator/samples/a11y-anchor-is-valid/input.svelte
index 7b14a80c9f..6d0f77a308 100644
--- a/test/validator/samples/a11y-anchor-is-valid/input.svelte
+++ b/test/validator/samples/a11y-anchor-is-valid/input.svelte
@@ -1,3 +1,4 @@
 <a>not actually a link</a>
 <a href=''>invalid</a>
-<a href='#'>invalid</a>
\ No newline at end of file
+<a href='#'>invalid</a>
+<a href="javascript:void(0)">invalid</a>
\ No newline at end of file
diff --git a/test/validator/samples/a11y-anchor-is-valid/warnings.json b/test/validator/samples/a11y-anchor-is-valid/warnings.json
index 532c44ad24..9438a74f5b 100644
--- a/test/validator/samples/a11y-anchor-is-valid/warnings.json
+++ b/test/validator/samples/a11y-anchor-is-valid/warnings.json
@@ -43,5 +43,20 @@
 			"character": 61
 		},
 		"pos": 53
+	},
+	{
+		"code": "a11y-invalid-attribute",
+		"message": "A11y: 'javascript:void(0)' is not a valid href attribute",
+		"start": {
+			"line": 4,
+			"column": 3,
+			"character": 77
+		},
+		"end": {
+			"line": 4,
+			"column": 28,
+			"character": 102
+		},
+		"pos": 77
 	}
 ]