diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 918db0a8f2da80eb17d679333d95d5ed0d99d82f..d10a658e3d27c977c720c7e42a4408affc758ee0 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -2117,10 +2117,15 @@ write_eventlog(int level, const char *line, int len)
 	 * try to convert the message to UTF16 and write it with ReportEventW().
 	 * Fall back on ReportEventA() if conversion failed.
 	 *
+	 * Since we palloc the structure required for conversion, also fall
+	 * through to writing unconverted if we have not yet set up
+	 * CurrentMemoryContext.
+	 *
 	 * Also verify that we are not on our way into error recursion trouble due
 	 * to error messages thrown deep inside pgwin32_message_to_UTF16().
 	 */
 	if (!in_error_recursion_trouble() &&
+		CurrentMemoryContext != NULL &&
 		GetMessageEncoding() != GetACPEncoding())
 	{
 		utf16 = pgwin32_message_to_UTF16(line, len, NULL);
diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index ca7f129ebe138c1c7657104f5058e3d03ab02358..e6f9151574dae0eaed25400f1f73bd14ffa3bf85 100644
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -1049,8 +1049,10 @@ GetMessageEncoding(void)
 
 #ifdef WIN32
 /*
- * Result is palloc'ed null-terminated utf16 string. The character length
- * is also passed to utf16len if not null. Returns NULL iff failed.
+ * Convert from MessageEncoding to a palloc'ed, null-terminated utf16
+ * string. The character length is also passed to utf16len if not
+ * null. Returns NULL iff failed. Before MessageEncoding initialization, "str"
+ * should be ASCII-only; this will function as though MessageEncoding is UTF8.
  */
 WCHAR *
 pgwin32_message_to_UTF16(const char *str, int len, int *utf16len)