diff --git a/runtime/lua/vim/filetype/detect.lua b/runtime/lua/vim/filetype/detect.lua
index 79cc6651c4..49739dba4f 100644
--- a/runtime/lua/vim/filetype/detect.lua
+++ b/runtime/lua/vim/filetype/detect.lua
@@ -936,10 +936,10 @@ function M.inc(path, bufnr)
     elseif findany(line, { '^%s{', '^%s%(%*' }) or matchregex(line, pascal_keywords) then
       return 'pascal'
     elseif
-      matchregex(line, [[\<\%(require\|inherit\)\>]])
+      matchregex(line, [[^\s*\<\%(require\|inherit\)\>]])
       or matchregex(
         line,
-        [=[[A-Z][A-Za-z0-9_:${}/]*\(\[[A-Za-z0-9_:/]\+\]\)*\s\+\%(??\|[?:+.]\)\?=.\? ]=]
+        [=[^\s*[A-Z][A-Za-z0-9_:${}/]*\%(\[[A-Za-z0-9_:/]\+\]\)*\s\+\%(??=\|[?:+.]=\|=[+.]\?\)\s\+]=]
       )
     then
       return 'bitbake'
diff --git a/test/old/testdir/test_filetype.vim b/test/old/testdir/test_filetype.vim
index c84c9c4b88..fa4d96247a 100644
--- a/test/old/testdir/test_filetype.vim
+++ b/test/old/testdir/test_filetype.vim
@@ -2817,11 +2817,17 @@ endfunc
 func Test_inc_file()
   filetype on
 
+  " pov
   call writefile(['this is the fallback'], 'Xfile.inc', 'D')
   split Xfile.inc
   call assert_equal('pov', &filetype)
   bwipe!
 
+  call writefile(['!Comment with formular a = b/c'], 'Xfile.inc')
+  split Xfile.inc
+  call assert_equal('pov', &filetype)
+  bwipe!
+
   " ObjectScript routine
   call writefile(['ROUTINE Sample [Type=INC]'], 'Xfile.inc', 'D')
   split Xfile.inc
@@ -2874,6 +2880,11 @@ func Test_inc_file()
   call assert_equal('bitbake', &filetype)
   bwipe!
 
+  call writefile(['MACHINE ?= "qemu"'], 'Xfile.inc')
+  split Xfile.inc
+  call assert_equal('bitbake', &filetype)
+  bwipe!
+
   call writefile(['MACHINE ??= "qemu"'], 'Xfile.inc')
   split Xfile.inc
   call assert_equal('bitbake', &filetype)