diff --git a/compat/mingw.c b/compat/mingw.c
index aa6d646443..714caa6991 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1094,7 +1094,7 @@ static wchar_t *make_environment_block(char **deltaenv)
 	char **tmpenv;
 	int i = 0, size = environ_size, wenvsz = 0, wenvpos = 0;
 
-	while (deltaenv && deltaenv[i])
+	while (deltaenv && deltaenv[i] && *deltaenv[i])
 		i++;
 
 	/* copy the environment, leaving space for changes */
@@ -1102,11 +1102,11 @@ static wchar_t *make_environment_block(char **deltaenv)
 	memcpy(tmpenv, environ, size * sizeof(char*));
 
 	/* merge supplied environment changes into the temporary environment */
-	for (i = 0; deltaenv && deltaenv[i]; i++)
+	for (i = 0; deltaenv && deltaenv[i] && *deltaenv[i]; i++)
 		size = do_putenv(tmpenv, deltaenv[i], size, 0);
 
 	/* create environment block from temporary environment */
-	for (i = 0; tmpenv[i]; i++) {
+	for (i = 0; tmpenv[i] && *tmpenv[i]; i++) {
 		size = 2 * strlen(tmpenv[i]) + 2; /* +2 for final \0 */
 		ALLOC_GROW(wenvblk, (wenvpos + size) * sizeof(wchar_t), wenvsz);
 		wenvpos += xutftowcs(&wenvblk[wenvpos], tmpenv[i], size) + 1;