diff --git a/core/src/mindustry/entities/comp/PlayerComp.java b/core/src/mindustry/entities/comp/PlayerComp.java
index 834d4c239a..5c340b8afe 100644
--- a/core/src/mindustry/entities/comp/PlayerComp.java
+++ b/core/src/mindustry/entities/comp/PlayerComp.java
@@ -65,10 +65,13 @@ abstract class PlayerComp implements UnitController, Entityc, Syncc, Timerc, Dra
         return team.core();
     }
 
-    /** @return largest/closest core, with largest cores getting priority */
+    /** @return largest/closest core, with the largest cores getting priority */
     @Nullable
     public CoreBuild bestCore(){
-        return team.cores().min(Structs.comps(Structs.comparingInt(c -> -c.block.size), Structs.comparingFloat(c -> c.dst(x, y))));
+        var cores = team.cores();
+        //if someone screws up the map and adds an invalid core, prioritize the core that's supported
+        //if there's only one core, there are no other options
+        return cores.min(b -> cores.size == 1 || ((CoreBlock)b.block).unitType.supportsEnv(state.rules.env), Structs.comps(Structs.comparingInt(c -> -c.block.size), Structs.comparingFloat(c -> c.dst2(x, y))));
     }
 
     public TextureRegion icon(){
diff --git a/core/src/mindustry/ui/dialogs/ResearchDialog.java b/core/src/mindustry/ui/dialogs/ResearchDialog.java
index abc8f66aa0..13bfcd6617 100644
--- a/core/src/mindustry/ui/dialogs/ResearchDialog.java
+++ b/core/src/mindustry/ui/dialogs/ResearchDialog.java
@@ -606,10 +606,15 @@ public class ResearchDialog extends BaseDialog{
 
             TechNode node = (TechNode)button.userObject;
 
-            infoTable.exited(() -> {
-                if(hoverNode == button && !infoTable.hasMouse() && !hoverNode.hasMouse()){
-                    hoverNode = null;
-                    rebuild();
+            infoTable.addListener(new InputListener(){
+                @Override
+                public void exit(InputEvent event, float x, float y, int pointer, Element fromActor){
+                    Element e = Core.scene.hit(x, y, true);
+
+                    if(hoverNode == button && !(e != null && (e.isDescendantOf(infoTable) || e.isDescendantOf(hoverNode))) && (Core.app.isDesktop() || pointer == 0)){
+                        hoverNode = null;
+                        rebuild();
+                    }
                 }
             });