diff --git a/libs/ui/imui.c b/libs/ui/imui.c
index 2b55b6381..75ecc2d28 100644
--- a/libs/ui/imui.c
+++ b/libs/ui/imui.c
@@ -478,9 +478,10 @@ calc_expansions (imui_ctx_t *ctx, hierarchy_t *h)
 				len[child].x = len[i].x;
 //				printf ("xc:%d p:%d l:%d\n", child, len[i].x, len[child].x);
 			} else {
-				uint32_t space = len[i].x - tlen.x;
+				int space = len[i].x - tlen.x;
 				int *p = Ent_GetComponent (ent[child], c_percent_x, reg);
-				len[child].x += *p * space / elen.x;
+				int delta = *p * space / elen.x;
+				len[child].x += max (delta, 0);
 //				printf ("xc:%d p:%d s:%d e:%d: l:%d\n", child, *p, space,
 //						elen.x, len[child].x);
 			}
@@ -491,9 +492,10 @@ calc_expansions (imui_ctx_t *ctx, hierarchy_t *h)
 				continue;
 			}
 			if (cont[i].vertical) {
-				uint32_t space = len[i].y - tlen.y;
+				int space = len[i].y - tlen.y;
 				int *p = Ent_GetComponent (ent[child], c_percent_y, reg);
-				len[child].y += *p * space / elen.y;
+				int delta = *p * space / elen.y;
+				len[child].y += max (delta, 0);
 //				printf ("yc:%d p:%d s:%d e:%d: l:%d\n", child, *p, space,
 //						elen.y, len[child].y);
 			} else {