diff --git a/repos/base/include/base/allocator_avl.h b/repos/base/include/base/allocator_avl.h
index b32cb84a2..0dd6e1ac5 100644
--- a/repos/base/include/base/allocator_avl.h
+++ b/repos/base/include/base/allocator_avl.h
@@ -94,19 +94,24 @@ class Genode::Allocator_avl_base : public Range_allocator
 				 */
 				void recompute();
 
-				/**
-				 * Accessor functions
-				 */
-				inline int    id()            { return _id; }
-				inline addr_t addr()          { return _addr; }
-				inline size_t avail()         { return _used ? 0 : _size; }
-				inline size_t size()          { return _size; }
-				inline bool   used()          { return _used; }
-				inline size_t max_avail()     { return _max_avail; }
-				inline void   used(bool used) { _used = used; }
+
+				/*****************
+				 ** Accessorors **
+				 *****************/
+
+				inline int    id()        const { return _id; }
+				inline addr_t addr()      const { return _addr; }
+				inline size_t avail()     const { return _used ? 0 : _size; }
+				inline size_t size()      const { return _size; }
+				inline bool   used()      const { return _used; }
+				inline size_t max_avail() const { return _max_avail; }
+
+				inline void used(bool used) { _used = used; }
+
 
 				enum { FREE = false, USED = true };
 
+
 				/**
 				 * Constructor
 				 *
diff --git a/repos/base/include/base/slab.h b/repos/base/include/base/slab.h
index b00a35d26..c42126b32 100644
--- a/repos/base/include/base/slab.h
+++ b/repos/base/include/base/slab.h
@@ -94,7 +94,7 @@ class Genode::Slab_block
 		/**
 		 * Request number of available entries in block
 		 */
-		unsigned avail() { return _avail; }
+		unsigned avail() const { return _avail; }
 
 		/**
 		 * Allocate slab entry from block
@@ -182,10 +182,10 @@ class Genode::Slab : public Allocator
 
 	public:
 
-		inline size_t slab_size()  { return _slab_size;  }
-		inline size_t block_size() { return _block_size; }
-		inline size_t num_elem()   { return _num_elem;   }
-		inline size_t entry_size() { return sizeof(Slab_entry) + _slab_size; }
+		inline size_t slab_size()  const { return _slab_size;  }
+		inline size_t block_size() const { return _block_size; }
+		inline size_t num_elem()   const { return _num_elem;   }
+		inline size_t entry_size() const { return sizeof(Slab_entry) + _slab_size; }
 
 		/**
 		 * Constructor