diff --git a/src/if_python.c b/src/if_python.c
index c9ebf13..4f23ffa 100644
--- a/src/if_python.c
+++ b/src/if_python.c
@@ -2080,7 +2080,7 @@
 	    return -1;
 
 	/* When column is out of range silently correct it. */
-	len = STRLEN(ml_get_buf(this->win->w_buffer, lnum, FALSE));
+	len = (long)STRLEN(ml_get_buf(this->win->w_buffer, lnum, FALSE));
 	if (col > len)
 	    col = len;