diff --git a/src/backend/libpq/be-secure.c b/src/backend/libpq/be-secure.c
index 6f38b2c7292..3f4c15dd259 100644
--- a/src/backend/libpq/be-secure.c
+++ b/src/backend/libpq/be-secure.c
@@ -729,6 +729,12 @@ initialize_SSL(void)
 					(errmsg("could not create SSL context: %s",
 							SSLerrmessage())));
 
+		/*
+		 * Disable OpenSSL's moving-write-buffer sanity check, because it
+		 * causes unnecessary failures in nonblocking send cases.
+		 */
+		SSL_CTX_set_mode(SSL_context, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
+
 		/*
 		 * Load and verify certificate and private key
 		 */
diff --git a/src/interfaces/libpq/fe-secure.c b/src/interfaces/libpq/fe-secure.c
index e7cd2a4561e..422ef1f1090 100644
--- a/src/interfaces/libpq/fe-secure.c
+++ b/src/interfaces/libpq/fe-secure.c
@@ -947,6 +947,12 @@ init_ssl_system(PGconn *conn)
 #endif
 			return -1;
 		}
+
+		/*
+		 * Disable OpenSSL's moving-write-buffer sanity check, because it
+		 * causes unnecessary failures in nonblocking send cases.
+		 */
+		SSL_CTX_set_mode(SSL_context, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
 	}
 
 #ifdef ENABLE_THREAD_SAFETY