diff --git a/src/core/config/mac.h b/src/core/config/mac.h
index 2503d65bf..bee1dea9f 100644
--- a/src/core/config/mac.h
+++ b/src/core/config/mac.h
@@ -46,7 +46,7 @@
  *
  */
 #ifndef OPENTHREAD_CONFIG_MAC_MAX_CSMA_BACKOFFS_DIRECT
-#define OPENTHREAD_CONFIG_MAC_MAX_CSMA_BACKOFFS_DIRECT 32
+#define OPENTHREAD_CONFIG_MAC_MAX_CSMA_BACKOFFS_DIRECT 4
 #endif
 
 /**