diff --git a/libsrc/osic1p/osic1p.inc b/libsrc/osic1p/osic1p.inc
index b5d48f32e..d209b258d 100644
--- a/libsrc/osic1p/osic1p.inc
+++ b/libsrc/osic1p/osic1p.inc
@@ -6,5 +6,5 @@ KBD             := $DF00        ; Polled keyboard register
 
 ; Other definitions
 VIDEORAMSIZE    = $0400         ; Size of C1P video RAM (1 kB)
-SCR_WIDTH       = $19           ; Screen width
+SCR_WIDTH       = $18           ; Screen width
 SCR_HEIGHT      = $19           ; Screen height