diff --git a/src/BearSSLClient.h b/src/BearSSLClient.h
index 1d54e5c..031cc0b 100644
--- a/src/BearSSLClient.h
+++ b/src/BearSSLClient.h
@@ -38,11 +38,11 @@
 #else
 
 #ifndef BEAR_SSL_CLIENT_OBUF_SIZE
-#define BEAR_SSL_CLIENT_OBUF_SIZE 512 + 85
+#define BEAR_SSL_CLIENT_OBUF_SIZE (512 + 85)
 #endif
 
 #ifndef BEAR_SSL_CLIENT_IBUF_SIZE
-#define BEAR_SSL_CLIENT_IBUF_SIZE 8192 + 85 + 325 - BEAR_SSL_CLIENT_OBUF_SIZE
+#define BEAR_SSL_CLIENT_IBUF_SIZE (8192 + 85 + 325 - BEAR_SSL_CLIENT_OBUF_SIZE)
 #endif
 
 #endif