diff --git a/src/debug/printing/printable_uart.cpp b/src/debug/printing/printable_uart.cpp
index 76a63f8..f3f7453 100644
--- a/src/debug/printing/printable_uart.cpp
+++ b/src/debug/printing/printable_uart.cpp
@@ -19,7 +19,9 @@ namespace sta
 
     void PrintableUART::print(const char * str, size_t length)
     {
+    	intf_->acquire();
         intf_->transfer(reinterpret_cast<const uint8_t *>(str), length);
+        intf_->release();
     }
 
 } // namespace sta