diff --git a/apps/ocsp.c b/apps/ocsp.c
index 3ee6dfb5e..3dc36c4bd 100644
--- a/apps/ocsp.c
+++ b/apps/ocsp.c
@@ -1227,7 +1227,7 @@ static int send_ocsp_response(BIO *cbio, OCSP_RESPONSE *resp)
 		return 0;
 	BIO_printf(cbio, http_resp, i2d_OCSP_RESPONSE(resp, NULL));
 	i2d_OCSP_RESPONSE_bio(cbio, resp);
-	BIO_flush(cbio);
+	(void)BIO_flush(cbio);
 	return 1;
 	}
 
diff --git a/apps/rand.c b/apps/rand.c
index a89389603..c3b26c466 100644
--- a/apps/rand.c
+++ b/apps/rand.c
@@ -213,7 +213,7 @@ int MAIN(int argc, char **argv)
 		BIO_write(out, buf, chunk);
 		num -= chunk;
 		}
-	BIO_flush(out);
+	(void)BIO_flush(out);
 
 	app_RAND_write_file(NULL, bio_err);
 	ret = 0;
diff --git a/apps/s_cb.c b/apps/s_cb.c
index 9a35d46ad..b4992aa62 100644
--- a/apps/s_cb.c
+++ b/apps/s_cb.c
@@ -573,5 +573,5 @@ void MS_CALLBACK msg_cb(int write_p, int version, int content_type, const void *
 			BIO_printf(bio, " ...");
 		BIO_printf(bio, "\n");
 		}
-	BIO_flush(bio);
+	(void)BIO_flush(bio);
 	}
diff --git a/apps/s_client.c b/apps/s_client.c
index 3f302c5f1..6df534fa7 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -668,7 +668,7 @@ re_start:
 			goto end;
 			}
 
-		BIO_ctrl_set_connected(sbio, 1, &peer);
+		(void)BIO_ctrl_set_connected(sbio, 1, &peer);
 
 		if ( enable_timeouts)
 			{
@@ -752,7 +752,7 @@ re_start:
 		while (mbuf_len>3 && mbuf[3]=='-');
 		/* STARTTLS command requires EHLO... */
 		BIO_printf(fbio,"EHLO openssl.client.net\r\n");
-		BIO_flush(fbio);
+		(void)BIO_flush(fbio);
 		/* wait for multi-line response to end EHLO SMTP response */
 		do
 			{
@@ -761,7 +761,7 @@ re_start:
 				foundit=1;
 			}
 		while (mbuf_len>3 && mbuf[3]=='-');
-		BIO_flush(fbio);
+		(void)BIO_flush(fbio);
 		BIO_pop(fbio);
 		BIO_free(fbio);
 		if (!foundit)
@@ -785,7 +785,7 @@ re_start:
 		BIO_gets(fbio,mbuf,BUFSIZZ);
 		/* STARTTLS command requires CAPABILITY... */
 		BIO_printf(fbio,". CAPABILITY\r\n");
-		BIO_flush(fbio);
+		(void)BIO_flush(fbio);
 		/* wait for multi-line CAPABILITY response */
 		do
 			{
@@ -794,7 +794,7 @@ re_start:
 				foundit=1;
 			}
 		while (mbuf_len>3 && mbuf[0]!='.');
-		BIO_flush(fbio);
+		(void)BIO_flush(fbio);
 		BIO_pop(fbio);
 		BIO_free(fbio);
 		if (!foundit)
@@ -814,7 +814,7 @@ re_start:
 			mbuf_len = BIO_gets(fbio,mbuf,BUFSIZZ);
 			}
 		while (mbuf_len>3 && mbuf[3]=='-');
-		BIO_flush(fbio);
+		(void)BIO_flush(fbio);
 		BIO_pop(fbio);
 		BIO_free(fbio);
 		BIO_printf(sbio,"AUTH TLS\r\n");
@@ -1303,6 +1303,6 @@ static void print_stuff(BIO *bio, SSL *s, int full)
 	if (peer != NULL)
 		X509_free(peer);
 	/* flush, or debugging output gets mixed with http response */
-	BIO_flush(bio);
+	(void)BIO_flush(bio);
 	}
 
diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index b746a50dd..7e6d30037 100644
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -1142,7 +1142,7 @@ dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
         SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
     s->d1->retransmitting = 0;
 
-    BIO_flush(SSL_get_wbio(s));
+    (void)BIO_flush(SSL_get_wbio(s));
     return ret;
     }