diff --git a/src/os_win32.c b/src/os_win32.c
index 300045b..07befb8 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -273,11 +273,12 @@
     static DWORD
 get_build_number(void)
 {
-    OSVERSIONINFOW	osver = {sizeof(OSVERSIONINFOW)};
+    OSVERSIONINFOW	osver;
     HMODULE		hNtdll;
     PfnRtlGetVersion	pRtlGetVersion;
     DWORD		ver = MAKE_VER(0, 0, 0);
 
+    osver.dwOSVersionInfoSize = sizeof(OSVERSIONINFOW);
     hNtdll = GetModuleHandle("ntdll.dll");
     if (hNtdll != NULL)
     {
@@ -325,7 +326,7 @@
 read_console_input(
     HANDLE	    hInput,
     INPUT_RECORD    *lpBuffer,
-    DWORD	    nLength,
+    int		    nLength,
     LPDWORD	    lpEvents)
 {
     enum
@@ -423,7 +424,7 @@
     DWORD	    nLength UNUSED,
     LPDWORD	    lpEvents)
 {
-    return read_console_input(hInput, lpBuffer, (DWORD)-1, lpEvents);
+    return read_console_input(hInput, lpBuffer, -1, lpEvents);
 }
 
 # ifdef FEAT_CLIENTSERVER
@@ -435,7 +436,7 @@
     DWORD    dwMilliseconds,
     DWORD    dwWakeMask)
 {
-    if (read_console_input(NULL, NULL, (DWORD)-2, NULL))
+    if (read_console_input(NULL, NULL, -2, NULL))
 	return WAIT_OBJECT_0;
     return MsgWaitForMultipleObjects(nCount, pHandles, fWaitAll,
 				     dwMilliseconds, dwWakeMask);
@@ -448,7 +449,7 @@
     HANDLE hHandle,
     DWORD dwMilliseconds)
 {
-    if (read_console_input(NULL, NULL, (DWORD)-2, NULL))
+    if (read_console_input(NULL, NULL, -2, NULL))
 	return WAIT_OBJECT_0;
     return WaitForSingleObject(hHandle, dwMilliseconds);
 }
@@ -760,8 +761,8 @@
     }
 
     // The bind_textdomain_codeset() function is optional.
-    dyn_libintl_bind_textdomain_codeset = (void *)GetProcAddress(hLibintlDLL,
-						   "bind_textdomain_codeset");
+    dyn_libintl_bind_textdomain_codeset = (char *(*)(const char *, const char *))
+			GetProcAddress(hLibintlDLL, "bind_textdomain_codeset");
     if (dyn_libintl_bind_textdomain_codeset == NULL)
 	dyn_libintl_bind_textdomain_codeset =
 					 null_libintl_bind_textdomain_codeset;
@@ -769,7 +770,8 @@
     // _wputenv() function for the libintl.dll is optional.
     hmsvcrt = find_imported_module_by_funcname(hLibintlDLL, "getenv");
     if (hmsvcrt != NULL)
-	dyn_libintl_wputenv = (void *)GetProcAddress(hmsvcrt, "_wputenv");
+	dyn_libintl_wputenv = (int (*)(const wchar_t *))
+					GetProcAddress(hmsvcrt, "_wputenv");
     if (dyn_libintl_wputenv == NULL || dyn_libintl_wputenv == _wputenv)
 	dyn_libintl_wputenv = null_libintl_wputenv;
 
@@ -4224,7 +4226,7 @@
 		      s == NULL ? l : (DWORD)(s - (lp + written)),
 		      &len, NULL);
 	}
-	if (len == (int)l)
+	if (len == l)
 	{
 	    // Finished a line, add a NL, unless this line should not have
 	    // one.
@@ -8338,7 +8340,7 @@
 
 
     static void CALLBACK
-set_flag(void *param, BOOLEAN unused2)
+set_flag(void *param, BOOLEAN unused2 UNUSED)
 {
     int *timeout_flag = (int *)param;