diff --git a/man/dwebp.1 b/man/dwebp.1
index 840b4ad6..02afed00 100644
--- a/man/dwebp.1
+++ b/man/dwebp.1
@@ -57,7 +57,7 @@ Don't use the in-loop filtering process even if it is required by
 the bitstream. This may produce visible blocks on the non-compliant output,
 but it will make the decoding faster.
 .TP
-.B \-dither " strength
+.BI \-dither " strength
 Specify a dithering \fBstrength\fP between 0 and 100. Dithering is a
 post-processing effect applied to chroma components in lossy compression.
 It helps by smoothing gradients and avoiding banding artifacts.