diff --git a/P25TX.cpp b/P25TX.cpp
index 8b4ffca..6ad8b3e 100644
--- a/P25TX.cpp
+++ b/P25TX.cpp
@@ -192,6 +192,6 @@ void CP25TX::setTXDelay(uint8_t delay)
 
 uint16_t CP25TX::getSpace() const
 {
-  return m_buffer.getSpace() / P25_LDU_FRAME_LENGTH_BYTES;
+  return m_buffer.getSpace() / (P25_LDU_FRAME_LENGTH_BYTES + 1U);
 }