diff --git a/BUILDING b/BUILDING
index ee6b0ab9..cf239e9a 100644
--- a/BUILDING
+++ b/BUILDING
@@ -25,4 +25,9 @@ BORINGSSL_IMPLEMENTATION. On Windows, where functions need to be tagged with
 BORINGSSL_SHARED_LIBRARY defined in the code which #includes the BoringSSL
 headers.
 
+To build on Windows, Yasm[2] is required for assembly. Either ensure yasm.exe
+is in %PATH% or configure CMAKE_ASM_NASM_COMPILER appropriately. Note that
+full Windows support is still in progress.
+
 [1] http://martine.github.io/ninja/
+[2] http://yasm.tortall.net/
diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index f98c7c86..d820e823 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -10,18 +10,16 @@ elseif(UNIX)
 	enable_language(ASM)
 else()
 	if (CMAKE_CL_64)
-		message("Using masm")
-		set(PERLASM_STYLE masm)
-		enable_language(ASM_MASM)
+		message("Using nasm")
+		set(PERLASM_STYLE nasm)
 	else()
 		message("Using win32n")
 		set(PERLASM_STYLE win32n)
-
-		# On 32-bit, upstream supports only NASM, not MASM. We'll use Yasm, specifically.
-		set(CMAKE_ASM_NASM_COMPILER "yasm")
-		enable_language(ASM_NASM)
 	endif()
+
+	# On Windows, we use the NASM output, specifically built with Yasm.
 	set(ASM_EXT asm)
+	enable_language(ASM_NASM)
 endif()
 
 function(perlasm dest src)