diff --git a/model/src/main/java/lcsb/mapviewer/model/map/species/Complex.java b/model/src/main/java/lcsb/mapviewer/model/map/species/Complex.java
index 82e91dfb97405d0d835a5f7f31f1fbf69754aba9..aa1feea06af525ac8790a758415aacedb54b6136 100644
--- a/model/src/main/java/lcsb/mapviewer/model/map/species/Complex.java
+++ b/model/src/main/java/lcsb/mapviewer/model/map/species/Complex.java
@@ -182,7 +182,9 @@ public class Complex extends Species {
 
   public void setStructuralState(StructuralState structuralState) {
     this.structuralState = structuralState;
-    structuralState.setSpecies(this);
+    if (structuralState != null) {
+      structuralState.setSpecies(this);
+    }
   }
 
 }
diff --git a/model/src/main/java/lcsb/mapviewer/model/map/species/Protein.java b/model/src/main/java/lcsb/mapviewer/model/map/species/Protein.java
index dcee676e7aa35d380dde5b91a127e648d57ff7e5..b9103e922d0453101306d6c9825347e0e0fd12e0 100644
--- a/model/src/main/java/lcsb/mapviewer/model/map/species/Protein.java
+++ b/model/src/main/java/lcsb/mapviewer/model/map/species/Protein.java
@@ -119,7 +119,9 @@ public abstract class Protein extends Species implements SpeciesWithBindingRegio
 
   public void setStructuralState(StructuralState structuralState) {
     this.structuralState = structuralState;
-    structuralState.setSpecies(this);
+    if (structuralState != null) {
+      structuralState.setSpecies(this);
+    }
   }
 
 }