diff --git a/repos/dde_bsd/src/lib/audio/mem.cc b/repos/dde_bsd/src/lib/audio/mem.cc
index 7a6383e6fc..29233c8f97 100644
--- a/repos/dde_bsd/src/lib/audio/mem.cc
+++ b/repos/dde_bsd/src/lib/audio/mem.cc
@@ -114,7 +114,7 @@ class Bsd::Slab_backend_alloc : public Genode::Allocator,
 			return _range.alloc(size, out_addr);
 		}
 
-		void           free(void *addr, Genode::size_t size) { }
+		void           free(void *addr, Genode::size_t size) { _range.free(addr, size); }
 		Genode::size_t overhead(Genode::size_t size) const   { return  0; }
 		bool           need_size_for_free() const override   { return false; }
 };
diff --git a/repos/dde_ipxe/src/lib/dde_ipxe/dde_support.cc b/repos/dde_ipxe/src/lib/dde_ipxe/dde_support.cc
index 94afd1bc63..9e3a9adf74 100644
--- a/repos/dde_ipxe/src/lib/dde_ipxe/dde_support.cc
+++ b/repos/dde_ipxe/src/lib/dde_ipxe/dde_support.cc
@@ -497,7 +497,7 @@ struct Slab_backend_alloc : public Genode::Allocator,
 		return _range.alloc(size, out_addr);
 	}
 
-	void           free(void *addr, Genode::size_t size) { }
+	void           free(void *addr, Genode::size_t size) { _range.free(addr, size); }
 	Genode::size_t overhead(Genode::size_t size) const   { return 0; }
 	bool           need_size_for_free() const            { return false; }
 };
diff --git a/repos/dde_linux/src/include/lx_emul/impl/internal/slab_backend_alloc.h b/repos/dde_linux/src/include/lx_emul/impl/internal/slab_backend_alloc.h
index f0c5450ff3..e36ee91ae3 100644
--- a/repos/dde_linux/src/include/lx_emul/impl/internal/slab_backend_alloc.h
+++ b/repos/dde_linux/src/include/lx_emul/impl/internal/slab_backend_alloc.h
@@ -106,7 +106,7 @@ class Lx::Slab_backend_alloc : public Genode::Allocator,
 			return _range.alloc(size, out_addr);
 		}
 
-		void   free(void *addr, size_t /* size */) override { }
+		void   free(void *addr, size_t size) override { _range.free(addr, size); }
 		size_t overhead(size_t size) const override { return  0; }
 		bool need_size_for_free() const override { return false; }
 
diff --git a/repos/dde_linux/src/lib/lxip/lxcc_emul.cc b/repos/dde_linux/src/lib/lxip/lxcc_emul.cc
index b5bab2f074..7c0782c3fa 100644
--- a/repos/dde_linux/src/lib/lxip/lxcc_emul.cc
+++ b/repos/dde_linux/src/lib/lxip/lxcc_emul.cc
@@ -115,7 +115,7 @@ class Genode::Slab_backend_alloc : public Genode::Allocator,
 				return _range.alloc(size, out_addr);
 		}
 
-		void   free(void *addr, size_t /* size */) override { }
+		void   free(void *addr, size_t size) override { _range.free(addr, size); }
 		size_t overhead(size_t size) const override { return  0; }
 		bool need_size_for_free() const override { return false; }
 
diff --git a/repos/dde_linux/src/lib/usb/lx_emul.cc b/repos/dde_linux/src/lib/usb/lx_emul.cc
index d86983ea45..04cf17ebbd 100644
--- a/repos/dde_linux/src/lib/usb/lx_emul.cc
+++ b/repos/dde_linux/src/lib/usb/lx_emul.cc
@@ -110,12 +110,8 @@ class Genode::Slab_backend_alloc : public Genode::Allocator,
 				return _range.alloc(size, out_addr);
 		}
 
-		void free(void *addr)
-		{
-			_range.free(addr);
-		}
-
-		void   free(void *addr, size_t /* size */) override { }
+		void   free(void *addr) { _range.free(addr); }
+		void   free(void *addr, size_t size) override { _range.free(addr, size); }
 		size_t overhead(size_t size) const override { return  0; }
 		bool need_size_for_free() const override { return false; }
 
diff --git a/repos/dde_linux/src/lib/wifi/lxcc_emul.cc b/repos/dde_linux/src/lib/wifi/lxcc_emul.cc
index bb74bcea4f..79f46c75df 100644
--- a/repos/dde_linux/src/lib/wifi/lxcc_emul.cc
+++ b/repos/dde_linux/src/lib/wifi/lxcc_emul.cc
@@ -119,7 +119,7 @@ class Lx::Slab_backend_alloc : public Genode::Allocator,
 			return _range.alloc(size, out_addr);
 		}
 
-		void   free(void *addr, size_t /* size */) override { }
+		void   free(void *addr, size_t size) override { _range.free(addr, size); }
 		size_t overhead(size_t size) const override { return  0; }
 		bool need_size_for_free() const override { return false; }