diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 5fc16be849..fe3af855d8 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -4419,7 +4419,6 @@ internal_cancel(SockAddr *raddr, int be_pid, int be_key,
 {
 	int			save_errno = SOCK_ERRNO;
 	pgsocket	tmpsock = PGINVALID_SOCKET;
-	char		sebuf[PG_STRERROR_R_BUFLEN];
 	int			maxlen;
 	struct
 	{
@@ -4498,8 +4497,25 @@ cancel_errReturn:
 	maxlen = errbufsize - strlen(errbuf) - 2;
 	if (maxlen >= 0)
 	{
-		strncat(errbuf, SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)),
-				maxlen);
+		/*
+		 * We can't invoke strerror here, since it's not signal-safe.  Settle
+		 * for printing the decimal value of errno.  Even that has to be done
+		 * the hard way.
+		 */
+		int			val = SOCK_ERRNO;
+		char		buf[32];
+		char	   *bufp;
+
+		bufp = buf + sizeof(buf) - 1;
+		*bufp = '\0';
+		do
+		{
+			*(--bufp) = (val % 10) + '0';
+			val /= 10;
+		} while (val > 0);
+		bufp -= 6;
+		memcpy(bufp, "error ", 6);
+		strncat(errbuf, bufp, maxlen);
 		strcat(errbuf, "\n");
 	}
 	if (tmpsock != PGINVALID_SOCKET)