diff --git a/internal/printer/utilities.go b/internal/printer/utilities.go
index cc3839cba5..9fdcb764d4 100644
--- a/internal/printer/utilities.go
+++ b/internal/printer/utilities.go
@@ -909,6 +909,12 @@ func newLineCharacterCache(source sourcemap.Source) *lineCharacterCache {
 // getLineAndCharacter returns the 0-based line number and UTF-16 code unit
 // offset from the start of that line for the given byte position.
 func (c *lineCharacterCache) getLineAndCharacter(pos int) (line int, character core.UTF16Offset) {
+	// Synthetic tokens (e.g. auto-inserted '}' for an unclosed block) can have
+	// positions beyond the end of the source text. Clamp to match JS semantics
+	// where string.slice(start, end) silently caps end at string.length.
+	if pos > len(c.text) {
+		pos = len(c.text)
+	}
 	line = scanner.ComputeLineOfPosition(c.lineMap, pos)
 	if c.hasCached && line == c.cachedLine && pos >= c.cachedPos {
 		// Incremental: only count UTF-16 code units from the last cached position.
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.errors.txt b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.errors.txt
new file mode 100644
index 0000000000..3342b22839
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.errors.txt
@@ -0,0 +1,9 @@
+sourceMapEmitUnclosedBlock.ts(2,1): error TS1005: '}' expected.
+
+
+==== sourceMapEmitUnclosedBlock.ts (1 errors) ====
+    {
+    
+    
+!!! error TS1005: '}' expected.
+!!! related TS1007 sourceMapEmitUnclosedBlock.ts:1:1: The parser expected to find a '}' to match the '{' token here.
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js
new file mode 100644
index 0000000000..1e211f0ebb
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js
@@ -0,0 +1,11 @@
+//// [tests/cases/compiler/sourceMapEmitUnclosedBlock.ts] ////
+
+//// [sourceMapEmitUnclosedBlock.ts]
+{
+
+
+//// [sourceMapEmitUnclosedBlock.js]
+"use strict";
+{
+}
+//# sourceMappingURL=sourceMapEmitUnclosedBlock.js.map
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js.map b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js.map
new file mode 100644
index 0000000000..361cf33207
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.js.map
@@ -0,0 +1,3 @@
+//// [sourceMapEmitUnclosedBlock.js.map]
+{"version":3,"file":"sourceMapEmitUnclosedBlock.js","sourceRoot":"","sources":["sourceMapEmitUnclosedBlock.ts"],"names":[],"mappings":";AAAA,CAAC;AACD,CAAA,AADC"}
+//// https://sokra.github.io/source-map-visualization#base64,InVzZSBzdHJpY3QiOw0Kew0KfQ0KLy8jIHNvdXJjZU1hcHBpbmdVUkw9c291cmNlTWFwRW1pdFVuY2xvc2VkQmxvY2suanMubWFw,eyJ2ZXJzaW9uIjozLCJmaWxlIjoic291cmNlTWFwRW1pdFVuY2xvc2VkQmxvY2suanMiLCJzb3VyY2VSb290IjoiIiwic291cmNlcyI6WyJzb3VyY2VNYXBFbWl0VW5jbG9zZWRCbG9jay50cyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiO0FBQUEsQ0FBQztBQUNELENBQUEsQUFEQyJ9,ewo=
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.sourcemap.txt b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.sourcemap.txt
new file mode 100644
index 0000000000..f7979924df
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.sourcemap.txt
@@ -0,0 +1,34 @@
+===================================================================
+JsFile: sourceMapEmitUnclosedBlock.js
+mapUrl: sourceMapEmitUnclosedBlock.js.map
+sourceRoot: 
+sources: sourceMapEmitUnclosedBlock.ts
+===================================================================
+-------------------------------------------------------------------
+emittedFile:sourceMapEmitUnclosedBlock.js
+sourceFile:sourceMapEmitUnclosedBlock.ts
+-------------------------------------------------------------------
+>>>"use strict";
+>>>{
+1 >
+2 >^
+3 > ^->
+1 >
+2 >{
+1 >Emitted(2, 1) Source(1, 1) + SourceIndex(0)
+2 >Emitted(2, 2) Source(1, 2) + SourceIndex(0)
+---
+>>>}
+1->
+2 >^
+3 > 
+4 > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^->
+1->
+  >
+2 >
+3 > 
+1->Emitted(3, 1) Source(2, 1) + SourceIndex(0)
+2 >Emitted(3, 2) Source(2, 1) + SourceIndex(0)
+3 >Emitted(3, 2) Source(1, 2) + SourceIndex(0)
+---
+>>>//# sourceMappingURL=sourceMapEmitUnclosedBlock.js.map
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.symbols b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.symbols
new file mode 100644
index 0000000000..ada130f0aa
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.symbols
@@ -0,0 +1,5 @@
+//// [tests/cases/compiler/sourceMapEmitUnclosedBlock.ts] ////
+
+=== sourceMapEmitUnclosedBlock.ts ===
+{
+
diff --git a/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.types b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.types
new file mode 100644
index 0000000000..ada130f0aa
--- /dev/null
+++ b/testdata/baselines/reference/compiler/sourceMapEmitUnclosedBlock.types
@@ -0,0 +1,5 @@
+//// [tests/cases/compiler/sourceMapEmitUnclosedBlock.ts] ////
+
+=== sourceMapEmitUnclosedBlock.ts ===
+{
+
diff --git a/testdata/tests/cases/compiler/sourceMapEmitUnclosedBlock.ts b/testdata/tests/cases/compiler/sourceMapEmitUnclosedBlock.ts
new file mode 100644
index 0000000000..f4e9b063f4
--- /dev/null
+++ b/testdata/tests/cases/compiler/sourceMapEmitUnclosedBlock.ts
@@ -0,0 +1,3 @@
+// @sourceMap: true
+
+{