diff --git a/dlls/advpack/tests/advpack.c b/dlls/advpack/tests/advpack.c
index 8d7c5ebb485..5bd39f76fdb 100644
--- a/dlls/advpack/tests/advpack.c
+++ b/dlls/advpack/tests/advpack.c
@@ -189,14 +189,14 @@ static void delnode_test(void)
     ok (hr == S_OK, "DelNode failed deleting a directory containing multiple files\n");
 }
 
-static void append_str(char **str, const char *data, ...)
+static void WINAPIV append_str(char **str, const char *data, ...)
 {
-    va_list valist;
+    __ms_va_list valist;
 
-    va_start(valist, data);
+    __ms_va_start(valist, data);
     vsprintf(*str, data, valist);
     *str += strlen(*str);
-    va_end(valist);
+    __ms_va_end(valist);
 }
 
 static void create_inf_file(void)
diff --git a/dlls/kernel32/tests/debugger.c b/dlls/kernel32/tests/debugger.c
index a85fe59e423..f62a614a97c 100644
--- a/dlls/kernel32/tests/debugger.c
+++ b/dlls/kernel32/tests/debugger.c
@@ -42,13 +42,13 @@ static BOOL (WINAPI *pIsDebuggerPresent)(void);
 
 static LONG child_failures;
 
-static void WINETEST_PRINTF_ATTR(2, 3) test_child_ok(int condition, const char *msg, ...)
+static void WINAPIV WINETEST_PRINTF_ATTR(2, 3) test_child_ok(int condition, const char *msg, ...)
 {
-    va_list valist;
+    __ms_va_list valist;
 
-    va_start(valist, msg);
+    __ms_va_start(valist, msg);
     winetest_vok(condition, msg, valist);
-    va_end(valist);
+    __ms_va_end(valist);
     if (!condition) ++child_failures;
 }
 
diff --git a/dlls/kernel32/tests/process.c b/dlls/kernel32/tests/process.c
index f62f8fb0ba1..c593ebe9b0e 100644
--- a/dlls/kernel32/tests/process.c
+++ b/dlls/kernel32/tests/process.c
@@ -281,15 +281,15 @@ static void     get_file_name(char* buf)
  *		static void     childPrintf
  *
  */
-static void WINETEST_PRINTF_ATTR(2,3) childPrintf(HANDLE h, const char* fmt, ...)
+static void WINAPIV WINETEST_PRINTF_ATTR(2,3) childPrintf(HANDLE h, const char* fmt, ...)
 {
-    va_list     valist;
+    __ms_va_list valist;
     char        buffer[1024+4*MAX_LISTED_ENV_VAR];
     DWORD       w;
 
-    va_start(valist, fmt);
+    __ms_va_start(valist, fmt);
     vsprintf(buffer, fmt, valist);
-    va_end(valist);
+    __ms_va_end(valist);
     WriteFile(h, buffer, strlen(buffer), &w, NULL);
 }
 
diff --git a/dlls/msi/tests/custom.c b/dlls/msi/tests/custom.c
index 3a189efff68..f994ad4c18a 100644
--- a/dlls/msi/tests/custom.c
+++ b/dlls/msi/tests/custom.c
@@ -34,15 +34,15 @@
 
 static int todo_level, todo_do_loop;
 
-static void ok_(MSIHANDLE hinst, int todo, const char *file, int line, int condition, const char *msg, ...)
+static void WINAPIV ok_(MSIHANDLE hinst, int todo, const char *file, int line, int condition, const char *msg, ...)
 {
     static char buffer[2000];
     MSIHANDLE record;
-    va_list valist;
+    __ms_va_list valist;
 
-    va_start(valist, msg);
+    __ms_va_start(valist, msg);
     vsprintf(buffer, msg, valist);
-    va_end(valist);
+    __ms_va_end(valist);
 
     record = MsiCreateRecord(5);
     MsiRecordSetInteger(record, 1, todo);
diff --git a/dlls/msi/tests/db.c b/dlls/msi/tests/db.c
index 181301e1fe9..64edcb98c03 100644
--- a/dlls/msi/tests/db.c
+++ b/dlls/msi/tests/db.c
@@ -36,15 +36,15 @@ static const char *mstfile = "winetst-db.mst";
 static const WCHAR msifileW[] = {'w','i','n','e','t','e','s','t','-','d','b','.','m','s','i',0};
 static const WCHAR msifile2W[] = {'w','i','n','e','t','s','t','2','-','d','b','.','m','s','i',0};
 
-static void check_record_(int line, MSIHANDLE rec, UINT count, ...)
+static void WINAPIV check_record_(int line, MSIHANDLE rec, UINT count, ...)
 {
-    va_list args;
+    __ms_va_list args;
     UINT i;
 
     ok_(__FILE__, line)(count == MsiRecordGetFieldCount(rec),
             "expected %u fields, got %u\n", count, MsiRecordGetFieldCount(rec));
 
-    va_start(args, count);
+    __ms_va_start(args, count);
 
     for (i = 1; i <= count; ++i)
     {
@@ -57,7 +57,7 @@ static void check_record_(int line, MSIHANDLE rec, UINT count, ...)
                 "field %u: expected \"%s\", got \"%s\"\n", i, expect, buffer);
     }
 
-    va_end(args);
+    __ms_va_end(args);
 }
 #define check_record(rec, ...) check_record_(__LINE__, rec, __VA_ARGS__)
 
diff --git a/dlls/msvcirt/tests/Makefile.in b/dlls/msvcirt/tests/Makefile.in
index 17955cfffac..340d2e00996 100644
--- a/dlls/msvcirt/tests/Makefile.in
+++ b/dlls/msvcirt/tests/Makefile.in
@@ -1,4 +1,3 @@
 TESTDLL   = msvcirt.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS    = msvcirt.c
diff --git a/dlls/msvcp100/tests/Makefile.in b/dlls/msvcp100/tests/Makefile.in
index 3414a300fd0..8d0a4ef893d 100644
--- a/dlls/msvcp100/tests/Makefile.in
+++ b/dlls/msvcp100/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp100.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	misc.c \
diff --git a/dlls/msvcp110/tests/Makefile.in b/dlls/msvcp110/tests/Makefile.in
index 30d02aa894a..e064826b2d2 100644
--- a/dlls/msvcp110/tests/Makefile.in
+++ b/dlls/msvcp110/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp110.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcp110.c
diff --git a/dlls/msvcp120/tests/Makefile.in b/dlls/msvcp120/tests/Makefile.in
index fc0869951ac..088a2164148 100644
--- a/dlls/msvcp120/tests/Makefile.in
+++ b/dlls/msvcp120/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp120.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcp120.c
diff --git a/dlls/msvcp140/tests/Makefile.in b/dlls/msvcp140/tests/Makefile.in
index fde164b1a22..aa82d0cba06 100644
--- a/dlls/msvcp140/tests/Makefile.in
+++ b/dlls/msvcp140/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp140.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcp140.c
diff --git a/dlls/msvcp60/tests/Makefile.in b/dlls/msvcp60/tests/Makefile.in
index 037f00f6b1c..5bc1aaa334a 100644
--- a/dlls/msvcp60/tests/Makefile.in
+++ b/dlls/msvcp60/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp60.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	ios.c \
diff --git a/dlls/msvcp90/tests/Makefile.in b/dlls/msvcp90/tests/Makefile.in
index 59bfadac2be..3dfaf0b303e 100644
--- a/dlls/msvcp90/tests/Makefile.in
+++ b/dlls/msvcp90/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcp90.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	ios.c \
diff --git a/dlls/msvcr100/tests/Makefile.in b/dlls/msvcr100/tests/Makefile.in
index 97480bb6cc3..a7652df38d2 100644
--- a/dlls/msvcr100/tests/Makefile.in
+++ b/dlls/msvcr100/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcr100.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcr100.c
diff --git a/dlls/msvcr110/tests/Makefile.in b/dlls/msvcr110/tests/Makefile.in
index e8fa81889df..e9ece8c1a80 100644
--- a/dlls/msvcr110/tests/Makefile.in
+++ b/dlls/msvcr110/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcr110.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcr110.c
diff --git a/dlls/msvcr120/tests/Makefile.in b/dlls/msvcr120/tests/Makefile.in
index 5a88f38d276..9898cbae117 100644
--- a/dlls/msvcr120/tests/Makefile.in
+++ b/dlls/msvcr120/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcr120.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcr120.c
diff --git a/dlls/msvcr90/tests/Makefile.in b/dlls/msvcr90/tests/Makefile.in
index 172e14626f9..9db8275e020 100644
--- a/dlls/msvcr90/tests/Makefile.in
+++ b/dlls/msvcr90/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcr90.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	msvcr90.c
diff --git a/dlls/msvcrt/tests/Makefile.in b/dlls/msvcrt/tests/Makefile.in
index 0867ac01ffe..da1b55e5a95 100644
--- a/dlls/msvcrt/tests/Makefile.in
+++ b/dlls/msvcrt/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcrt.dll
-APPMODE   = -mno-cygwin
 EXTRAINCL = -I$(srcdir)/..
 IMPORTS   = advapi32
 
diff --git a/dlls/msvcrtd/tests/Makefile.in b/dlls/msvcrtd/tests/Makefile.in
index d86815a8239..d72b1d6a16d 100644
--- a/dlls/msvcrtd/tests/Makefile.in
+++ b/dlls/msvcrtd/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = msvcrtd.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	debug.c
diff --git a/dlls/shell32/tests/shlexec.c b/dlls/shell32/tests/shlexec.c
index dbf2f88a373..496006985cf 100644
--- a/dlls/shell32/tests/shlexec.c
+++ b/dlls/shell32/tests/shlexec.c
@@ -117,15 +117,15 @@ static char* decodeA(const char* str)
     return ptr;
 }
 
-static void WINETEST_PRINTF_ATTR(2,3) childPrintf(HANDLE h, const char* fmt, ...)
+static void WINAPIV WINETEST_PRINTF_ATTR(2,3) childPrintf(HANDLE h, const char* fmt, ...)
 {
-    va_list     valist;
+    __ms_va_list valist;
     char        buffer[1024];
     DWORD       w;
 
-    va_start(valist, fmt);
+    __ms_va_start(valist, fmt);
     vsprintf(buffer, fmt, valist);
-    va_end(valist);
+    __ms_va_end(valist);
     WriteFile(h, buffer, strlen(buffer), &w, NULL);
 }
 
@@ -351,16 +351,16 @@ static void dump_child_(const char* file, int line)
  ***/
 
 static char shell_call[2048];
-static void WINETEST_PRINTF_ATTR(2,3) _okShell(int condition, const char *msg, ...)
+static void WINAPIV WINETEST_PRINTF_ATTR(2,3) _okShell(int condition, const char *msg, ...)
 {
-    va_list valist;
+    __ms_va_list valist;
     char buffer[2048];
 
     strcpy(buffer, shell_call);
     strcat(buffer, " ");
-    va_start(valist, msg);
+    __ms_va_start(valist, msg);
     vsprintf(buffer+strlen(buffer), msg, valist);
-    va_end(valist);
+    __ms_va_end(valist);
     winetest_ok(condition, "%s", buffer);
 }
 #define okShell_(file, line) (winetest_set_location(file, line), 0) ? (void)0 : _okShell
diff --git a/dlls/ucrtbase/tests/Makefile.in b/dlls/ucrtbase/tests/Makefile.in
index bdd259dcf4f..3fd4b1c7d38 100644
--- a/dlls/ucrtbase/tests/Makefile.in
+++ b/dlls/ucrtbase/tests/Makefile.in
@@ -1,5 +1,4 @@
 TESTDLL   = ucrtbase.dll
-APPMODE   = -mno-cygwin
 
 C_SRCS = \
 	cpp.c \
diff --git a/programs/services/tests/service.c b/programs/services/tests/service.c
index 5e9265d587f..f6e36fb6933 100644
--- a/programs/services/tests/service.c
+++ b/programs/services/tests/service.c
@@ -56,14 +56,14 @@ static inline void service_event(const char *event)
     send_msg("EVENT", event);
 }
 
-static void service_ok(int cnd, const char *msg, ...)
+static void WINAPIV service_ok(int cnd, const char *msg, ...)
 {
-   va_list valist;
-   char buf[512];
+    __ms_va_list valist;
+    char buf[512];
 
-    va_start(valist, msg);
+    __ms_va_start(valist, msg);
     vsprintf(buf, msg, valist);
-    va_end(valist);
+    __ms_va_end(valist);
 
     send_msg(cnd ? "OK" : "FAIL", buf);
 }
diff --git a/tools/makedep.c b/tools/makedep.c
index e4d48ddeb29..a051281c204 100644
--- a/tools/makedep.c
+++ b/tools/makedep.c
@@ -4029,6 +4029,7 @@ static void load_sources( struct makefile *make )
     make->extra_targets = get_expanded_make_var_array( make, "EXTRA_TARGETS" );
 
     if (make->module && strendswith( make->module, ".a" )) make->staticlib = make->module;
+    if (make->testdll) strarray_add( &make->extradllflags, "-mno-cygwin" );
 
     strarray_addall( &make->extradllflags, get_expanded_make_var_array( make, "APPMODE" ));
     make->disabled   = make->base_dir && strarray_exists( &disabled_dirs, make->base_dir );