diff --git a/src/absil/ilread.fs b/src/absil/ilread.fs
index 11acfcee40c..0f8baa91e6a 100644
--- a/src/absil/ilread.fs
+++ b/src/absil/ilread.fs
@@ -1049,6 +1049,7 @@ type ILReaderContext =
     userStringsStreamPhysicalLoc: int32;
     stringsStreamPhysicalLoc: int32;
     blobsStreamPhysicalLoc: int32;
+    blobsStreamSize: int32;
     readUserStringHeap: (int32 -> string);
     memoizeString: string -> string;
     readStringHeap: (int32 -> string);
@@ -1534,9 +1535,13 @@ let readStringHeapUncached ctxtH idx =
 let readStringHeap          ctxt idx = ctxt.readStringHeap idx 
 let readStringHeapOption   ctxt idx = if idx = 0 then None else Some (readStringHeap ctxt idx) 
 
+let emptyByteArray: byte[] = [||]
 let readBlobHeapUncached ctxtH idx = 
     let ctxt = getHole ctxtH
-    seekReadBlob ctxt.is (ctxt.blobsStreamPhysicalLoc + idx) 
+    // valid index lies in range [1..streamSize)
+    // NOTE: idx cannot be 0 - Blob\String heap has first empty element that is one byte 0
+    if idx <= 0 || idx >= ctxt.blobsStreamSize then emptyByteArray
+    else seekReadBlob ctxt.is (ctxt.blobsStreamPhysicalLoc + idx) 
 let readBlobHeap        ctxt idx = ctxt.readBlobHeap idx 
 let readBlobHeapOption ctxt idx = if idx = 0 then None else Some (readBlobHeap ctxt idx) 
 
@@ -3973,6 +3978,7 @@ let rec genOpenBinaryReader infile is opts =
                  userStringsStreamPhysicalLoc   = userStringsStreamPhysicalLoc;
                  stringsStreamPhysicalLoc       = stringsStreamPhysicalLoc;
                  blobsStreamPhysicalLoc         = blobsStreamPhysicalLoc;
+                 blobsStreamSize                = blobsStreamSize;
                  memoizeString                  = Tables.memoize id;
                  readUserStringHeap             = cacheUserStringHeap (readUserStringHeapUncached ctxtH);
                  readStringHeap                 = cacheStringHeap (readStringHeapUncached ctxtH);
diff --git a/tests/fsharp/core/ilread/Library.dll b/tests/fsharp/core/ilread/Library.dll
new file mode 100644
index 00000000000..7e724a12b20
Binary files /dev/null and b/tests/fsharp/core/ilread/Library.dll differ
diff --git a/tests/fsharp/core/ilread/build.bat b/tests/fsharp/core/ilread/build.bat
new file mode 100644
index 00000000000..8ee2cf351c6
--- /dev/null
+++ b/tests/fsharp/core/ilread/build.bat
@@ -0,0 +1,35 @@
+@if "%_echo%"=="" echo off
+
+setlocal
+REM Configure the sample, i.e. where to find the F# compiler and C# compiler.
+if EXIST build.ok DEL /f /q build.ok
+
+call %~d0%~p0..\..\..\config.bat
+@if ERRORLEVEL 1 goto Error
+
+if NOT "%FSC:NOTAVAIL=X%" == "%FSC%" ( 
+  REM Skipping test for FSI.EXE
+  goto Skip
+)
+
+"%FSC%" %fsc_flags% /r:Library.dll /out:test.exe test.fs
+@if ERRORLEVEL 1 goto Error
+
+"%PEVERIFY%" test.exe
+@if ERRORLEVEL 1 goto Error
+
+:Ok
+echo Built fsharp %~f0 ok.
+echo. > build.ok
+endlocal
+exit /b 0
+
+:Skip
+echo Skipped %~f0
+endlocal
+exit /b 0
+
+
+:Error
+endlocal
+exit /b %ERRORLEVEL%
diff --git a/tests/fsharp/core/ilread/run.bat b/tests/fsharp/core/ilread/run.bat
new file mode 100644
index 00000000000..2cbceb83a46
--- /dev/null
+++ b/tests/fsharp/core/ilread/run.bat
@@ -0,0 +1,22 @@
+@if "%_echo%"=="" echo off
+
+setlocal 
+dir build.ok > NUL ) || (
+  @echo 'build.ok' not found.
+  goto :ERROR
+)
+
+call %~d0%~p0..\..\..\config.bat
+
+%CLIX% .\test.exe
+if ERRORLEVEL 1 goto Error
+
+:Ok
+echo Ran fsharp %~f0 ok.
+endlocal
+exit /b 0
+
+:Error
+endlocal
+exit /b %ERRORLEVEL%
+
diff --git a/tests/fsharp/core/ilread/test.fs b/tests/fsharp/core/ilread/test.fs
new file mode 100644
index 00000000000..160a97cb9e1
--- /dev/null
+++ b/tests/fsharp/core/ilread/test.fs
@@ -0,0 +1,8 @@
+open Library
+
+[<EntryPoint>]
+let main _ =
+    let cls = Class1()
+    let len = cls.GetLength("123")
+    printfn "%O" len
+    if len = 3 then 0 else 1
\ No newline at end of file
diff --git a/tests/test.lst b/tests/test.lst
index 4489bbcb7f8..74ceee14e44 100644
--- a/tests/test.lst
+++ b/tests/test.lst
@@ -35,6 +35,7 @@ Core03		fsharp\core\innerpoly
 Core03,Smoke		fsharp\core\int32
 Core03		fsharp\core\internalsvisible
 Core03		fsharp\core\interop
+Core03		fsharp\core\ilread
 Core03		fsharp\core\lazy
 Core03		fsharp\core\letrec
 Core03,Smoke		fsharp\core\libtest