diff --git a/meson.build b/meson.build
index 27d1387315..e8d7d3ccc2 100644
--- a/meson.build
+++ b/meson.build
@@ -1042,7 +1042,7 @@ check_components = [
   ['user32', ['windows.h', 'winuser.h'], ['GetShellWindow'], ['user32']],
   ['vfw32', ['windows.h', 'vfw.h'], ['capCreateCaptureWindow'], ['vfw3']],
   ['vaapi', ['va/va.h'], ['vaInitialize'], ['va']],
-  ['zlib', ['zlib.h'], ['zlibVersion'], ['z']],
+  ['zlib', ['zlib.h'], ['zlibVersion'], ['z'], {'meson-dep': 'zlib'}],
 
   # Libraries with preconditions
   ['vaapi_drm', ['va/va.h', 'va/va_drm.h'], ['vaGetDisplayDRM'], ['va', 'va-drm'],
@@ -1930,6 +1930,7 @@ foreach check : all_checks
     prefix = ''
 
     found = true
+    skipchecks = false
 
     preconditions = opts.get('preconditions', [])
 
@@ -1985,6 +1986,11 @@ foreach check : all_checks
             req = false
           endif
           dep = cc.find_library(link_with, required : req)
+          if not dep.found() and opts.has_key('meson-dep')
+            dep = dependency(opts.get('meson-dep'), required: false)
+            # We can't do compiler checks for non-external dependencies, so skip them and trust the meson dependency
+            skipchecks = true
+          endif
           found = found and dep.found()
           extra_deps += dep
         endforeach
@@ -2014,7 +2020,8 @@ foreach check : all_checks
         else
           dep = dependency(pkg_name, required : req)
         endif
-        found = dep.found() and dep.type_name() != 'internal'
+        found = dep.found()
+        skipchecks = dep.type_name() == 'internal'  # same here, trust the meson dependency
         extra_deps += dep
       endif
     endif
@@ -2028,14 +2035,14 @@ foreach check : all_checks
         endif
 
         if not conf.has(header.underscorify())
-          has_header = cc.has_header(header, dependencies: extra_deps)
+          has_header = skipchecks or cc.has_header(header, dependencies: extra_deps)
           conf.set10(header.underscorify().to_lower(), has_header)
           found = found and has_header
         endif
       endforeach
     endif
 
-    if found
+    if found and not skipchecks
       n_funcs_found = 0
       foreach symbol : funcs
         if check_type == 'header-func'
@@ -2055,7 +2062,7 @@ foreach check : all_checks
       endif
     endif
 
-    if found
+    if found and not skipchecks
       n_defines_found = 0
       foreach symbol : defines
         if cc.get_define(symbol, dependencies : extra_deps, prefix: prefix, args : c_args + project_c_args) != ''
@@ -2065,15 +2072,15 @@ foreach check : all_checks
       found = n_defines_found == defines.length()
     endif
 
-    if found and compiles != ''
+    if found and compiles != '' and not skipchecks
       found = cc.compiles('\n\n'.join([prefix, compiles]), dependencies : extra_deps, args : c_args + project_c_args, name: name)
     endif
 
-    if found and links != ''
+    if found and links != '' and not skipchecks
       found = cc.links('\n\n'.join([prefix, links]), dependencies : extra_deps, args : c_args + project_c_args, name: name)
     endif
 
-    if found and type != ''
+    if found and type != '' and not skipchecks
       found = cc.has_type(type, prefix : prefix, dependencies : extra_deps, args : c_args + project_c_args)
     endif
 
@@ -3103,6 +3110,11 @@ foreach a: arch_list
 endforeach
 
 foreach have: have_list
+  if have == 'unistd_h' and conf.get(have) == 0
+    # an atrocious hack to get this working with the zlib subproject on windows...
+    # zlib also uses a HAVE_UNISTD_H define, but it checks it with #ifdef and not #if
+    continue
+  endif
   final_conf.set('HAVE_@0@'.format(have.to_upper()), conf.get(have.to_lower()))
 endforeach