diff --git a/ChangeLog b/ChangeLog
index 7cbd72cd..75bbc593 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,7 @@ What's New for OpenJPEG
 + : added
 
 October 31, 2006
+* [Antonin] fixed a bug in the computation of the mantissa (mu)
 + [Antonin] added the ability to specify the rate as "float" (before : integer)
 
 August 18, 2006
diff --git a/libopenjpeg/dwt.c b/libopenjpeg/dwt.c
index 702bf6cf..88527d67 100644
--- a/libopenjpeg/dwt.c
+++ b/libopenjpeg/dwt.c
@@ -603,7 +603,7 @@ void dwt_calc_explicit_stepsizes(opj_tccp_t * tccp, int prec) {
 			stepsize = 1.0;
 		} else {
 			double norm = dwt_norms_real[orient][level];
-			stepsize = (1 << (gain + 1)) / norm;
+			stepsize = (1 << (gain)) / norm;
 		}
 		dwt_encode_stepsize((int) floor(stepsize * 8192.0), prec + gain, &tccp->stepsizes[bandno]);
 	}