diff --git a/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/ProcedureSignature.java b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/ProcedureSignature.java
index 065d1ba00f9d2..d529a0ebd8b5b 100644
--- a/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/ProcedureSignature.java
+++ b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/ProcedureSignature.java
@@ -33,7 +33,7 @@
  * This describes the signature of a procedure, made up of its namespace, name, and input/output description.
  * Procedure uniqueness is currently *only* on the namespace/name level - no procedure overloading allowed (yet).
  */
-public class ProcedureSignature
+public class ProcedureSignature implements Signature
 {
     public static final List<FieldSignature> VOID = unmodifiableList( new ArrayList<>() );
 
@@ -65,6 +65,7 @@ public ProcedureSignature( QualifiedName name,
         this.warning = warning;
     }
 
+    @Override
     public QualifiedName name()
     {
         return name;
@@ -75,16 +76,19 @@ public Mode mode()
         return mode;
     }
 
+    @Override
     public Optional<String> deprecated()
     {
         return Optional.ofNullable( deprecated );
     }
 
+    @Override
     public String[] allowed()
     {
         return allowed;
     }
 
+    @Override
     public List<FieldSignature> inputSignature()
     {
         return inputSignature;
@@ -100,6 +104,7 @@ public boolean isVoid()
         return outputSignature == VOID;
     }
 
+    @Override
     public Optional<String> description()
     {
         return Optional.ofNullable( description );
diff --git a/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/Signature.java b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/Signature.java
new file mode 100644
index 0000000000000..7f86b57e4b281
--- /dev/null
+++ b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/Signature.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2002-2018 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.internal.kernel.api.procs;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface Signature
+{
+    QualifiedName name();
+
+    Optional<String> deprecated();
+
+    List<FieldSignature> inputSignature();
+
+    Optional<String> description();
+
+    String[] allowed();
+}
diff --git a/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/UserFunctionSignature.java b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/UserFunctionSignature.java
index b861c0531f47c..c6cf674879df2 100644
--- a/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/UserFunctionSignature.java
+++ b/community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/procs/UserFunctionSignature.java
@@ -34,7 +34,7 @@
  * This describes the signature of a function, made up of its namespace, name, and input/output description.
  * Function uniqueness is currently *only* on the namespace/name level - no function overloading allowed (yet).
  */
-public final class UserFunctionSignature
+public final class UserFunctionSignature implements Signature
 {
     private final QualifiedName name;
     private final List<FieldSignature> inputSignature;
@@ -58,16 +58,19 @@ public UserFunctionSignature( QualifiedName name,
         this.allowed = allowed;
     }
 
+    @Override
     public QualifiedName name()
     {
         return name;
     }
 
+    @Override
     public Optional<String> deprecated()
     {
         return Optional.ofNullable( deprecated );
     }
 
+    @Override
     public List<FieldSignature> inputSignature()
     {
         return inputSignature;
@@ -78,11 +81,13 @@ public Neo4jTypes.AnyType outputType()
         return type;
     }
 
+    @Override
     public Optional<String> description()
     {
         return Optional.ofNullable( description );
     }
 
+    @Override
     public String[] allowed()
     {
         return allowed;
diff --git a/community/kernel/src/main/java/org/neo4j/kernel/impl/proc/ProcedureHolder.java b/community/kernel/src/main/java/org/neo4j/kernel/impl/proc/ProcedureHolder.java
index 1dd6b63407a48..2651e0354c8e2 100644
--- a/community/kernel/src/main/java/org/neo4j/kernel/impl/proc/ProcedureHolder.java
+++ b/community/kernel/src/main/java/org/neo4j/kernel/impl/proc/ProcedureHolder.java
@@ -26,6 +26,7 @@
 import java.util.Map;
 
 import org.neo4j.internal.kernel.api.procs.QualifiedName;
+import org.neo4j.internal.kernel.api.procs.Signature;
 
 /**
  * Simple in memory store for procedures.
@@ -33,7 +34,7 @@
  * Should only be accessed from a single thread
  * @param <T> the type to be stored
  */
-class ProcedureHolder<T>
+class ProcedureHolder<T extends Signature>
 {
     private final Map<QualifiedName,Integer> nameToId = new HashMap<>();
     private final ArrayList<T> store = new ArrayList<>();