diff --git a/src/popupmnu.c b/src/popupmnu.c
index 4dd3a94..1d747a6 100644
--- a/src/popupmnu.c
+++ b/src/popupmnu.c
@@ -337,7 +337,7 @@
 
 				if (rt != NULL)
 				{
-				    len = STRLEN(rt);
+				    len = (int)STRLEN(rt);
 				    if (len > pum_width)
 				    {
 					for (j = pum_width; j < len; ++j)