diff --git a/storm/hash/Hashkey.cpp b/storm/hash/Hashkey.cpp
index d715370..96047e1 100644
--- a/storm/hash/Hashkey.cpp
+++ b/storm/hash/Hashkey.cpp
@@ -6,6 +6,10 @@ bool HASHKEY_NONE::operator==(const HASHKEY_NONE& key) {
     return true;
 }
 
+HASHKEY_PTR::HASHKEY_PTR(void* key) {
+    this->m_key = key;
+}
+
 bool HASHKEY_PTR::operator==(const HASHKEY_PTR& key) {
     return this->m_key == key.m_key;
 }
diff --git a/storm/hash/Hashkey.hpp b/storm/hash/Hashkey.hpp
index 11c8c30..877a372 100644
--- a/storm/hash/Hashkey.hpp
+++ b/storm/hash/Hashkey.hpp
@@ -7,6 +7,7 @@ class HASHKEY_PTR {
     void* m_key = nullptr;
 
     // Member functions
+    HASHKEY_PTR(void* key);
     bool operator==(const HASHKEY_PTR& key);
 };