diff --git a/internal/ls/lsconv/converters.go b/internal/ls/lsconv/converters.go
index 1728f3f7bcd..aba0e9b1140 100644
--- a/internal/ls/lsconv/converters.go
+++ b/internal/ls/lsconv/converters.go
@@ -2,7 +2,6 @@ package lsconv
 
 import (
 	"context"
-	"fmt"
 	"net/url"
 	"slices"
 	"strings"
@@ -149,13 +148,16 @@ func (c *Converters) LineAndCharacterToPosition(script Script, lineAndCharacter
 	line := core.TextPos(lineAndCharacter.Line)
 	char := core.TextPos(lineAndCharacter.Character)
 
-	if line < 0 || int(line) >= len(lineMap.LineStarts) {
-		panic(fmt.Sprintf("bad line number. Line: %d, lineMap length: %d", line, len(lineMap.LineStarts)))
+	if line < 0 {
+		line = 0
+	} else if int(line) >= len(lineMap.LineStarts) {
+		line = core.TextPos(len(lineMap.LineStarts) - 1)
 	}
 
+	textLen := core.TextPos(len(script.Text()))
 	start := lineMap.LineStarts[line]
 	if lineMap.AsciiOnly || c.positionEncoding == lsproto.PositionEncodingKindUTF8 {
-		return start + char
+		return min(start+char, textLen)
 	}
 
 	var utf8Char core.TextPos
@@ -170,7 +172,7 @@ func (c *Converters) LineAndCharacterToPosition(script Script, lineAndCharacter
 		utf8Char = core.TextPos(i + utf8.RuneLen(r))
 	}
 
-	return start + utf8Char
+	return min(start+utf8Char, textLen)
 }
 
 func (c *Converters) PositionToLineAndCharacter(script Script, position core.TextPos) lsproto.Position {
diff --git a/internal/project/session_test.go b/internal/project/session_test.go
index 9ba29853b0a..b27978d23bd 100644
--- a/internal/project/session_test.go
+++ b/internal/project/session_test.go
@@ -13,6 +13,7 @@ import (
 	"github.com/microsoft/typescript-go/internal/ls/lsutil"
 	"github.com/microsoft/typescript-go/internal/lsp/lsproto"
 	"github.com/microsoft/typescript-go/internal/project"
+	"github.com/microsoft/typescript-go/internal/testutil"
 	"github.com/microsoft/typescript-go/internal/testutil/projecttestutil"
 	"github.com/microsoft/typescript-go/internal/tspath"
 	"gotest.tools/v3/assert"
@@ -952,4 +953,50 @@ func TestSession(t *testing.T) {
 		assert.DeepEqual(t, *actualConfig2.TS(), *expectedPrefs1)
 		assert.DeepEqual(t, *actualConfig2.JS(), *expectedPrefs2)
 	})
+
+	t.Run("definition with stale position after file shrink does not panic", func(t *testing.T) {
+		t.Parallel()
+		defer testutil.RecoverAndFail(t, "Panic on definition with stale position")
+		files := map[string]any{
+			"/home/projects/TS/p1/tsconfig.json": `{"compilerOptions": {"noLib": true}}`,
+			"/home/projects/TS/p1/src/index.ts":  "0\n1\n",
+		}
+		session, _ := projecttestutil.Setup(files)
+		session.DidOpenFile(context.Background(), "file:///home/projects/TS/p1/src/index.ts", 1, "0\n1\n", lsproto.LanguageKindTypeScript)
+
+		session.DidChangeFile(context.Background(), "file:///home/projects/TS/p1/src/index.ts", 2, []lsproto.TextDocumentContentChangePartialOrWholeDocument{
+			{
+				Partial: &lsproto.TextDocumentContentChangePartial{
+					Range: lsproto.Range{
+						Start: lsproto.Position{Line: 0, Character: 0},
+						End:   lsproto.Position{Line: 2, Character: 0},
+					},
+					Text: "0\n",
+				},
+			},
+		})
+
+		ls, err := session.GetLanguageService(context.Background(), "file:///home/projects/TS/p1/src/index.ts")
+		assert.NilError(t, err)
+
+		_, err = ls.ProvideDefinition(context.Background(), "file:///home/projects/TS/p1/src/index.ts", lsproto.Position{Line: 2, Character: 0})
+		assert.NilError(t, err)
+	})
+
+	t.Run("definition with out-of-bounds position does not panic", func(t *testing.T) {
+		t.Parallel()
+		defer testutil.RecoverAndFail(t, "Panic on definition with out-of-bounds position")
+		files := map[string]any{
+			"/home/projects/TS/p1/tsconfig.json": `{"compilerOptions": {"noLib": true}}`,
+			"/home/projects/TS/p1/src/index.ts":  "let x = 1;",
+		}
+		session, _ := projecttestutil.Setup(files)
+		session.DidOpenFile(context.Background(), "file:///home/projects/TS/p1/src/index.ts", 1, "let x = 1;", lsproto.LanguageKindTypeScript)
+
+		ls, err := session.GetLanguageService(context.Background(), "file:///home/projects/TS/p1/src/index.ts")
+		assert.NilError(t, err)
+
+		_, err = ls.ProvideDefinition(context.Background(), "file:///home/projects/TS/p1/src/index.ts", lsproto.Position{Line: 999, Character: 0})
+		assert.NilError(t, err)
+	})
 }