diff --git a/src/energenie/drv/hrfm69.c b/src/energenie/drv/hrfm69.c
index c7d59d5..6960e45 100644
--- a/src/energenie/drv/hrfm69.c
+++ b/src/energenie/drv/hrfm69.c
@@ -3,6 +3,8 @@
  * Hope RF RFM69 radio controller low level register interface.
  */
 
+#include <stdlib.h>
+
 #include "system.h"
 #include "hrfm69.h"
 #include "spi.h"
diff --git a/src/energenie/drv/radio.c b/src/energenie/drv/radio.c
index a92ec56..b8ea7ec 100644
--- a/src/energenie/drv/radio.c
+++ b/src/energenie/drv/radio.c
@@ -368,8 +368,6 @@
     // and not on every FIFO load.
 
     int i;
-    uint8_t irqflags1;
-    uint8_t irqflags2;
 
     /* VALIDATE: Check input parameters are in range */
     if (times == 0 || len == 0) //TODO: make this an ASSERT()
@@ -410,9 +408,9 @@
 
     /* CONFIRM: Was the transmit ok? */
     // Check final flags in case of overruns etc
-    irqflags1 = HRF_readreg(HRF_ADDR_IRQFLAGS1);
-    irqflags2 = HRF_readreg(HRF_ADDR_IRQFLAGS2);
-
+#if defined(TRACE)
+    uint8_t irqflags1 = HRF_readreg(HRF_ADDR_IRQFLAGS1);
+    uint8_t irqflags2 = HRF_readreg(HRF_ADDR_IRQFLAGS2);
     TRACE_OUTS("irqflags1,2=");
     TRACE_OUTN(irqflags1);
     TRACE_OUTC(',');
@@ -424,6 +422,7 @@
     {
         TRACE_FAIL("FIFO not empty or overrun at end of burst");
     }
+#endif
 }
 
 
diff --git a/src/energenie/drv/trace.h b/src/energenie/drv/trace.h
index c281c4d..abf396a 100644
--- a/src/energenie/drv/trace.h
+++ b/src/energenie/drv/trace.h
@@ -11,20 +11,32 @@
 #ifndef _TRACE_H
 #define _TRACE_H
 
+//#define TRACE_POSIX
+
 /* POSIX IMPLEMENTATION */
 /* Printf is not available on some platforms, or not very efficient.
  * These macros make it possible to re-map I/O to more efficient functions.
  */
 
+#if defined(TRACE_POSIX)
 #include <stdio.h>
 #include <stdlib.h>
 
+#define TRACE
 #define TRACE_OUTS(S)   do{printf("%s", S);fflush(stdout);} while (0)
 #define TRACE_OUTN(N)   do{printf("%d", (unsigned int)N);fflush(stdout);} while (0)
 #define TRACE_OUTC(C)   putc(C, stdout)
 #define TRACE_NL()      do{TRACE_OUTC('\n');fflush(stdout);} while (0)
 #define TRACE_FAIL(msg) do{fprintf(stderr, "%s", msg);exit(-1);} while (0)
 
+#else // no trace defined
+
+#define TRACE_OUTS(S)
+#define TRACE_OUTN(N)
+#define TRACE_OUTC(C)
+#define TRACE_NL()
+#define TRACE_FAIL(M)
+#endif
 #endif
 
 /***** END OF FILE *****/
diff --git a/src/energenie/radio_rpi.so b/src/energenie/radio_rpi.so
index 05cefbf..0129587 100755
--- a/src/energenie/radio_rpi.so
+++ b/src/energenie/radio_rpi.so
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