diff --git a/Inc/FreeRTOSConfig.h b/Inc/FreeRTOSConfig.h
index 755e468..1663f5a 100644
--- a/Inc/FreeRTOSConfig.h
+++ b/Inc/FreeRTOSConfig.h
@@ -59,7 +59,7 @@
 #define configTICK_RATE_HZ                       ((TickType_t)1000)
 #define configMAX_PRIORITIES                     ( 7 )
 #define configMINIMAL_STACK_SIZE                 ((uint16_t)128)
-#define configTOTAL_HEAP_SIZE                    ((size_t)3072)
+#define configTOTAL_HEAP_SIZE                    ((size_t)2048)
 #define configMAX_TASK_NAME_LEN                  ( 16 )
 #define configUSE_16_BIT_TICKS                   0
 #define configUSE_MUTEXES                        1
diff --git a/STM32L433CCUx_FLASH.ld b/STM32L433CCUx_FLASH.ld
index f05aa52..457b692 100644
--- a/STM32L433CCUx_FLASH.ld
+++ b/STM32L433CCUx_FLASH.ld
@@ -4,7 +4,7 @@ ENTRY(Reset_Handler)
 /* Highest address of the user mode stack */
 _estack = 0x2000C000;    /* end of RAM */
 /* Generate a link error if heap and stack don't fit into RAM */
-_Min_Heap_Size = 0x400;      /* required amount of heap  */
+_Min_Heap_Size = 0x800;      /* required amount of heap  */
 _Min_Stack_Size = 0x400; /* required amount of stack */
 
 /* Specify the memory areas */
diff --git a/Src/main.c b/Src/main.c
index b2aa90a..5d03a85 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -1662,6 +1662,12 @@ void assert_failed(uint8_t* file, uint32_t line)
 }
 #endif /* USE_FULL_ASSERT */
 
+void vApplicationMallocFailedHook()
+{
+    snprintf(error_message, sizeof(error_message), "malloc failed");
+    while (1);
+}
+
 void vApplicationStackOverflowHook(TaskHandle_t xTask, signed char *pcTaskName)
 {
     snprintf(error_message, sizeof(error_message), "stack overflow %s", pcTaskName);
diff --git a/TNC/HdlcFrame.cpp b/TNC/HdlcFrame.cpp
index a101a7c..3ce60ef 100644
--- a/TNC/HdlcFrame.cpp
+++ b/TNC/HdlcFrame.cpp
@@ -17,12 +17,14 @@ IoFramePool& ioFramePool() {
 void release(IoFrame* frame)
 {
     ioFramePool().release(frame);
+//    printf("< %d\r\n", ioFramePool().size());
 }
 
 IoFrame* acquire()
 {
     auto result = ioFramePool().acquire();
     if (result == nullptr) CxxErrorHandler();
+//    printf("> %d\r\n", ioFramePool().size());
     return result;
 }
 
@@ -33,6 +35,7 @@ IoFrame* acquire_wait()
     while ((result = ioFramePool().acquire()) == nullptr) {
         osThreadYield();
     }
+//    printf("> %d\r\n", ioFramePool().size());
     return result;
 }
 
diff --git a/TNC/HdlcFrame.hpp b/TNC/HdlcFrame.hpp
index d37dea5..5aa919c 100644
--- a/TNC/HdlcFrame.hpp
+++ b/TNC/HdlcFrame.hpp
@@ -170,12 +170,10 @@ public:
             free_list_.pop_front();
         }
         taskEXIT_CRITICAL_FROM_ISR(x);
-        DEBUG("Acquired frame %p (size after = %d)", result, free_list_.size());
         return result;
     }
 
     void release(frame_type* frame) {
-        DEBUG("Released frame %p (size before = %d)", frame, free_list_.size());
         frame->clear();
         auto x = taskENTER_CRITICAL_FROM_ISR();
         free_list_.push_back(*frame);
diff --git a/TNC/KissHardware.cpp b/TNC/KissHardware.cpp
index aa8a4f9..7ce1305 100644
--- a/TNC/KissHardware.cpp
+++ b/TNC/KissHardware.cpp
@@ -43,10 +43,10 @@ int powerOffViaUSB(void)
 namespace mobilinkd { namespace tnc { namespace kiss {
 
 #ifdef NUCLEOTNC
-const char FIRMWARE_VERSION[] = "2.1.8";
+const char FIRMWARE_VERSION[] = "2.1.9";
 const char HARDWARE_VERSION[] = "Mobilinkd NucleoTNC";
 #else
-const char FIRMWARE_VERSION[] = "2.1.8";
+const char FIRMWARE_VERSION[] = "2.1.9";
 const char HARDWARE_VERSION[] = "Mobilinkd TNC3 2.1.1";
 #endif
 
diff --git a/TNC/M17Encoder.cpp b/TNC/M17Encoder.cpp
index 85a0819..0e91573 100644
--- a/TNC/M17Encoder.cpp
+++ b/TNC/M17Encoder.cpp
@@ -152,6 +152,13 @@ void M17Encoder::run()
     osThreadSuspend(encoderTaskHandle);
 }
 
+/**
+ *
+ * @param frame is the frame to transmit. Ownership has been transferred
+ *  and this function is responsible for either transferring ownership
+ *  downstream or releasing it.
+ * @param type is whether this is a basic packet or encapsulated packet.
+ */
 void M17Encoder::process_packet(tnc::hdlc::IoFrame* frame, FrameType type)
 {
     using namespace mobilinkd::tnc::kiss;
@@ -189,6 +196,7 @@ void M17Encoder::process_packet(tnc::hdlc::IoFrame* frame, FrameType type)
     default:
         ERROR("M17 encoder bad state");
     }
+    release(frame);
 }
 
 void M17Encoder::process_stream(tnc::hdlc::IoFrame* frame, FrameType type)
diff --git a/TNC/SerialPort.cpp b/TNC/SerialPort.cpp
index d270ed5..cf306e1 100644
--- a/TNC/SerialPort.cpp
+++ b/TNC/SerialPort.cpp
@@ -139,12 +139,11 @@ void startSerialTask(void const* arg)
         if (evt.value.v < FLASH_BASE) // Assumes FLASH_BASE < SRAM_BASE.
         {
             // Error received.
-            hdlc::release(frame);
+            frame->clear();
 #ifndef NUCLEOTNC
             ERROR("UART Error: %08lx", uart_error.load());
 #endif
             uart_error.store(HAL_UART_ERROR_NONE);
-            frame = hdlc::acquire_wait();
             HAL_UART_Receive_DMA(&huart_serial, rxBuffer, RX_BUFFER_SIZE * 2);
             __HAL_UART_ENABLE_IT(&huart_serial, UART_IT_IDLE);
             continue;
@@ -183,6 +182,7 @@ void startSerialTask(void const* arg)
                     if (hdlc::ioFramePool().size() < (hdlc::ioFramePool().capacity() / 4))
                     {
                         UART_DMAPauseReceive(&huart_serial);
+                        WARN("frame pool low");
                         while (hdlc::ioFramePool().size() < (hdlc::ioFramePool().capacity() / 2))
                         {
                             osThreadYield();
@@ -206,22 +206,19 @@ void startSerialTask(void const* arg)
                 switch (c) {
                 case TFESC:
                     if (not frame->push_back(FESC)) {
-                        hdlc::release(frame);
+                        frame->clear();
                         state = WAIT_FBEGIN;  // Drop frame;
-                        frame = hdlc::acquire_wait();
                     }
                     break;
                 case TFEND:
                     if (not frame->push_back(FEND)) {
-                        hdlc::release(frame);
+                        frame->clear();
                         state = WAIT_FBEGIN;  // Drop frame;
-                        frame = hdlc::acquire_wait();
                     }
                     break;
                 default:
-                    hdlc::release(frame);
+                    frame->clear();
                     state = WAIT_FBEGIN;  // Drop frame;
-                    frame = hdlc::acquire_wait();
                 }
                 break;
             }