diff --git a/cores/portduino/PortduinoPrint.cpp b/cores/portduino/PortduinoPrint.cpp
index b6de06a..1f74388 100644
--- a/cores/portduino/PortduinoPrint.cpp
+++ b/cores/portduino/PortduinoPrint.cpp
@@ -10,8 +10,10 @@ size_t Print::printf(const char *format, ...) {
                                 // Linux that is fine, TBD on MyNewt
     va_list args;
     va_start(args, format);
-    size_t n = vsnprintf(buf, sizeof(buf), format, args);
-    write(buf);
+    int n = vsnprintf(buf, sizeof(buf), format, args);
     va_end(args);
-    return n;
-}
\ No newline at end of file
+    if (n <= 0) return 0;
+    // vsnprintf returns the would-be length; clamp to what actually fit.
+    size_t len = (n < (int)sizeof(buf)) ? (size_t)n : sizeof(buf) - 1;
+    return write((const uint8_t *)buf, len);
+}