diff --git a/dcm.c b/dcm.c
index c3b6afe..32f0974 100644
--- a/dcm.c
+++ b/dcm.c
@@ -173,11 +173,13 @@ bool dcm_renormalise(float *v)
 
 void dcm_drift_correction(float x, float y, float z)
 {
-	float mag;
 	float weight;
 	float error[3];
 	int i;
 
+#if DCM_WEIGHT
+	float mag;
+
 	mag = (1.0/fisqrt(x*x+y*y+z*z)) / GRAVITY;
 
 	mag = 1-mag;
@@ -190,6 +192,9 @@ void dcm_drift_correction(float x, float y, float z)
 		weight = 0.0;
 	if (weight > 1.0)
 		weight = 1.0;
+#else
+	weight = 1.0;
+#endif
 
 	/* error = cross product of dcm last row and acceleration vector */
 	/* third row = cross product of first two rows */