diff --git a/BUILDING.md b/BUILDING.md
index 19b227af40..4a93b37efa 100644
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -258,6 +258,9 @@ Prerequisites:
 * Basic Unix tools required for some tests,
   [Git for Windows](http://git-scm.com/download/win) includes Git Bash
   and tools which can be included in the global `PATH`.
+* **Optional** (for OpenSSL assembler modules): the [NetWide Assembler](http://www.nasm.us/),
+  if not installed in the default location it needs to be manually added
+  to `PATH`.
 * **Optional** (to build the MSI): the [WiX Toolset v3.11](http://wixtoolset.org/releases/)
   and the [Wix Toolset Visual Studio 2017 Extension](https://marketplace.visualstudio.com/items?itemName=RobMensching.WixToolsetVisualStudio2017Extension).
 
diff --git a/tools/msvs/find_nasm.cmd b/tools/msvs/find_nasm.cmd
new file mode 100644
index 0000000000..d30d213116
--- /dev/null
+++ b/tools/msvs/find_nasm.cmd
@@ -0,0 +1,19 @@
+@IF NOT DEFINED DEBUG_HELPER @ECHO OFF
+
+ECHO Looking for NASM
+
+FOR /F "delims=" %%a IN ('where nasm 2^> NUL') DO (
+  EXIT /B 0
+)
+
+IF EXIST "%ProgramFiles%\NASM\nasm.exe" (
+  SET "Path=%Path%;%ProgramFiles%\NASM"
+  EXIT /B 0
+)
+
+IF EXIST "%ProgramFiles(x86)%\NASM\nasm.exe" (
+  SET "Path=%Path%;%ProgramFiles(x86)%\NASM"
+  EXIT /B 0
+)
+
+EXIT /B 1
diff --git a/vcbuild.bat b/vcbuild.bat
index f1353d114a..19e3d1881c 100644
--- a/vcbuild.bat
+++ b/vcbuild.bat
@@ -170,6 +170,9 @@ if "%target%"=="Clean" rmdir /S /Q %~dp0deps\icu
 call tools\msvs\find_python.cmd
 if errorlevel 1 goto :exit
 
+call tools\msvs\find_nasm.cmd
+if errorlevel 1 echo Could not find NASM, it will not be used.
+
 call :getnodeversion || exit /b 1
 
 if defined TAG set configure_flags=%configure_flags% --tag=%TAG%