diff --git a/compat/mingw.c b/compat/mingw.c
index ef9721fea21b5d..df827b7d20c64c 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -2228,12 +2228,12 @@ void mingw_startup()
 		__argv[i] = wcstoutfdup_startup(buffer, wargv[i], maxlen);
 	for (i = 0; wenv[i]; i++) {
 		environ[i] = wcstoutfdup_startup(buffer, wenv[i], maxlen);
-		if (strncasecmp(environ[i], "MSYS2_TZ=", 9)) {
+		if (strncasecmp(environ[i], "MSYS2_TZ=", 9) == 0) {
 			char *to_free = environ[i];
 			environ[i] = xstrdup(to_free + 6);
 			free(to_free);
 		}
-		if (strncasecmp(environ[i], "TMP=", 4)) {
+		if (strncasecmp(environ[i], "TMP=", 4) == 0) {
 			/*
 			 * Convert all dir separators to forward slashes,
 			 * to help shell commands called from the Git