diff --git a/firmware/tinyg/plan_arc.c b/firmware/tinyg/plan_arc.c
index 159a1057c..2713641e6 100755
--- a/firmware/tinyg/plan_arc.c
+++ b/firmware/tinyg/plan_arc.c
@@ -259,8 +259,9 @@ static stat_t _compute_arc()
     float end_0 = arc.gm.target[arc.plane_axis_0] - arc.position[arc.plane_axis_0] - arc.offset[arc.plane_axis_0];
     float end_1 = arc.gm.target[arc.plane_axis_1] - arc.position[arc.plane_axis_1] - arc.offset[arc.plane_axis_1];
     float err = fabs(hypotf(end_0, end_1) - arc.radius);   // end radius - start radius
-    if ( (err > ARC_RADIUS_ERROR_MAX) ||
-        ((err > ARC_RADIUS_ERROR_MIN) && (err > arc.radius * ARC_RADIUS_TOLERANCE)) ) {
+    if ( (err > ARC_RADIUS_ERROR_MAX) || 
+        ((err < ARC_RADIUS_ERROR_MIN) && 
+         (err > arc.radius * ARC_RADIUS_TOLERANCE)) ) {
 //        return (STAT_ARC_HAS_IMPOSSIBLE_CENTER_POINT);
         return (STAT_ARC_SPECIFICATION_ERROR);
     }
diff --git a/firmware/tinyg/plan_arc.h b/firmware/tinyg/plan_arc.h
index c12200543..6bd55a087 100755
--- a/firmware/tinyg/plan_arc.h
+++ b/firmware/tinyg/plan_arc.h
@@ -20,10 +20,6 @@
 #ifndef PLAN_ARC_H_ONCE
 #define PLAN_ARC_H_ONCE
 
-#ifdef __cplusplus
-extern "C"{
-#endif
-
 // Arc radius tests. See http://linuxcnc.org/docs/html/gcode/gcode.html#sec:G2-G3-Arc
 //#define ARC_RADIUS_ERROR_MAX    ((float)0.5)        // max allowable mm between start and end radius
 #define ARC_RADIUS_ERROR_MAX    ((float)1.0)        // max allowable mm between start and end radius
@@ -78,8 +74,4 @@ void cm_arc_init(void);
 stat_t cm_arc_callback(void);
 void cm_abort_arc(void);
 
-#ifdef __cplusplus
-}
-#endif
-
 #endif	// End of include guard: PLAN_ARC_H_ONCE
diff --git a/firmware/tinyg/tinyg.cproj b/firmware/tinyg/tinyg.cproj
index 9d9d69c58..843a0370e 100755
--- a/firmware/tinyg/tinyg.cproj
+++ b/firmware/tinyg/tinyg.cproj
@@ -83,7 +83,7 @@
         <InterfaceName>PDI</InterfaceName>
       </ToolOptions>
       <ToolType>com.atmel.avrdbg.tool.atmelice</ToolType>
-      <ToolNumber>J41800021149</ToolNumber>
+      <ToolNumber>J41800004081</ToolNumber>
       <ToolName>Atmel-ICE</ToolName>
     </com_atmel_avrdbg_tool_atmelice>
     <UseGdb>True</UseGdb>
diff --git a/firmware/tinyg/tinyg.h b/firmware/tinyg/tinyg.h
index 2ba4e51d2..e06136072 100755
--- a/firmware/tinyg/tinyg.h
+++ b/firmware/tinyg/tinyg.h
@@ -45,7 +45,7 @@
 /****** REVISIONS ******/
 
 #ifndef TINYG_FIRMWARE_BUILD
-#define TINYG_FIRMWARE_BUILD        440.19	// fix for Makercam / PartKam giant arcs
+#define TINYG_FIRMWARE_BUILD        440.20	// arc test
 
 #endif
 #define TINYG_FIRMWARE_VERSION		0.97					// firmware major version