diff --git a/src/popupwin.c b/src/popupwin.c
index 099a0c2..02aa83e 100644
--- a/src/popupwin.c
+++ b/src/popupwin.c
@@ -2463,7 +2463,12 @@
 								   / linecount;
 	    if (sb_thumb_height == 0)
 		sb_thumb_height = 1;
-	    sb_thumb_top = (wp->w_topline - 1 + (linecount / wp->w_height) / 2)
+	    if (linecount <= wp->w_height)
+		// it just fits, avoid divide by zero
+		sb_thumb_top = 0;
+	    else
+		sb_thumb_top = (wp->w_topline - 1
+				+ (linecount / wp->w_height) / 2)
 				* (wp->w_height - sb_thumb_height)
 						  / (linecount - wp->w_height);
 	    if (wp->w_scrollbar_highlight != NULL)
diff --git a/src/testdir/test_popupwin.vim b/src/testdir/test_popupwin.vim
index 4e798c6..3983b57 100644
--- a/src/testdir/test_popupwin.vim
+++ b/src/testdir/test_popupwin.vim
@@ -1565,6 +1565,18 @@
   call delete('XtestPopupScroll')
 endfunc
 
+func Test_popup_fitting_scrollbar()
+  " this was causing a crash, divide by zero
+  let winid = popup_create([
+	\ 'one', 'two', 'longer line that wraps', 'four', 'five'], {
+	\ 'scrollbar': 1,
+	\ 'maxwidth': 10,
+	\ 'maxheight': 5,
+	\ 'firstline': 2})
+  redraw
+  call popup_clear()
+endfunc
+
 func Test_popup_settext()
   if !CanRunVimInTerminal()
     throw 'Skipped: cannot make screendumps'
diff --git a/src/version.c b/src/version.c
index 634cd08..2c370da 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1636,
+/**/
     1635,
 /**/
     1634,