diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 75a855bbdd..c5d3422f62 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -414,12 +414,15 @@ There are many types of assembly languages that all use the same file name
 extensions.  Therefore you will have to select the type yourself, or add a
 line in the assembly file that Vim will recognize.  Currently these syntax
 files are included:
-	asm		GNU assembly (the default)
+	asm		GNU assembly (usually have .s or .S extension and were
+			already built using C compiler such as GCC or CLANG)
 	asm68k		Motorola 680x0 assembly
 	asmh8300	Hitachi H-8300 version of GNU assembly
 	ia64		Intel Itanium 64
 	fasm		Flat assembly (https://flatassembler.net)
-	masm		Microsoft assembly (probably works for any 80x86)
+	masm		Microsoft assembly (.masm files are compiled with
+			Microsoft's Macro Assembler. This is only supported
+			for x86, x86_64, ARM and AARCH64 CPU families)
 	nasm		Netwide assembly
 	tasm		Turbo Assembly (with opcodes 80x86 up to Pentium, and
 			MMX)
diff --git a/runtime/lua/vim/filetype.lua b/runtime/lua/vim/filetype.lua
index b983e7d1c6..8a51d2a9d3 100644
--- a/runtime/lua/vim/filetype.lua
+++ b/runtime/lua/vim/filetype.lua
@@ -743,6 +743,7 @@ local extension = {
   mkd = detect.markdown,
   markdown = detect.markdown,
   mdown = detect.markdown,
+  masm = 'masm',
   mhtml = 'mason',
   mason = 'mason',
   master = 'master',
@@ -805,6 +806,7 @@ local extension = {
   n1ql = 'n1ql',
   nql = 'n1ql',
   nanorc = 'nanorc',
+  nasm = 'nasm',
   NSA = 'natural',
   NSC = 'natural',
   NSG = 'natural',
diff --git a/test/old/testdir/test_filetype.vim b/test/old/testdir/test_filetype.vim
index 7e6a6dfac5..d1551885b1 100644
--- a/test/old/testdir/test_filetype.vim
+++ b/test/old/testdir/test_filetype.vim
@@ -114,6 +114,7 @@ func s:GetFilenameChecks() abort
     \ 'arduino': ['file.ino', 'file.pde'],
     \ 'art': ['file.art'],
     \ 'asciidoc': ['file.asciidoc', 'file.adoc'],
+    \ 'asm': ['file.s', 'file.S', 'file.a', 'file.A'],
     \ 'asn': ['file.asn', 'file.asn1'],
     \ 'asterisk': ['asterisk/file.conf', 'asterisk/file.conf-file', 'some-asterisk/file.conf', 'some-asterisk/file.conf-file'],
     \ 'astro': ['file.astro'],
@@ -453,6 +454,7 @@ func s:GetFilenameChecks() abort
     \ 'map': ['file.map'],
     \ 'maple': ['file.mv', 'file.mpl', 'file.mws'],
     \ 'markdown': ['file.markdown', 'file.mdown', 'file.mkd', 'file.mkdn', 'file.mdwn', 'file.md'],
+    \ 'masm': ['file.masm'],
     \ 'mason': ['file.mason', 'file.mhtml'],
     \ 'master': ['file.mas', 'file.master'],
     \ 'matlab': ['file.m'],
@@ -529,6 +531,7 @@ func s:GetFilenameChecks() abort
     \ 'n1ql': ['file.n1ql', 'file.nql'],
     \ 'named': ['namedfile.conf', 'rndcfile.conf', 'named-file.conf', 'named.conf', 'rndc-file.conf', 'rndc-file.key', 'rndc.conf', 'rndc.key'],
     \ 'nanorc': ['/etc/nanorc', 'file.nanorc', 'any/etc/nanorc'],
+    \ 'nasm': ['file.nasm'],
     \ 'natural': ['file.NSA', 'file.NSC', 'file.NSG', 'file.NSL', 'file.NSM', 'file.NSN', 'file.NSP', 'file.NSS'],
     \ 'ncf': ['file.ncf'],
     \ 'neomuttlog': ['/home/user/.neomuttdebug1'],