diff --git a/repos/os/include/gpu_session/gpu_session.h b/repos/os/include/gpu_session/gpu_session.h
index 0df7f45ffd..0008ddbef9 100644
--- a/repos/os/include/gpu_session/gpu_session.h
+++ b/repos/os/include/gpu_session/gpu_session.h
@@ -72,7 +72,7 @@ struct Gpu::Session : public Genode::Session
 	struct Conflicting_id : Genode::Exception { };
 	struct Mapping_buffer_failed  : Genode::Exception { };
 
-	enum { REQUIRED_QUOTA = 1024 * 1024, CAP_QUOTA = 8, };
+	enum { REQUIRED_QUOTA = 1024 * 1024, CAP_QUOTA = 256, };
 
 	static const char *service_name() { return "Gpu"; }
 
@@ -145,6 +145,8 @@ struct Gpu::Session : public Genode::Session
 	 * \param attrs     specify how the buffer is mapped
 	 *
 	 * \throw Mapping_buffer_failed
+	 * \throw Out_of_caps
+	 * \throw Out_of_ram
 	 */
 	virtual Genode::Dataspace_capability map_buffer(Buffer_id id,
 	                                                bool aperture,
@@ -164,6 +166,7 @@ struct Gpu::Session : public Genode::Session
 	 * \param va  virtual address
 	 *
 	 * \throw Mapping_buffer_failed
+	 * \throw Out_of_caps
 	 * \throw Out_of_ram
 	 */
 	virtual bool map_buffer_ppgtt(Buffer_id id, Gpu::addr_t va) = 0;
@@ -196,16 +199,16 @@ struct Gpu::Session : public Genode::Session
 	GENODE_RPC(Rpc_completion_sigh, void, completion_sigh,
 	           Genode::Signal_context_capability);
 	GENODE_RPC_THROW(Rpc_alloc_buffer, Genode::Dataspace_capability, alloc_buffer,
-	                 GENODE_TYPE_LIST(Out_of_ram),
+	                 GENODE_TYPE_LIST(Out_of_caps, Out_of_ram),
 	                 Gpu::Buffer_id, Genode::size_t);
 	GENODE_RPC(Rpc_free_buffer, void, free_buffer, Gpu::Buffer_id);
 	GENODE_RPC_THROW(Rpc_map_buffer, Genode::Dataspace_capability, map_buffer,
-	                 GENODE_TYPE_LIST(Mapping_buffer_failed, Out_of_ram),
+	                 GENODE_TYPE_LIST(Mapping_buffer_failed, Out_of_caps, Out_of_ram),
 	                 Gpu::Buffer_id, bool, Gpu::Mapping_attributes);
 	GENODE_RPC(Rpc_unmap_buffer, void, unmap_buffer,
 	           Gpu::Buffer_id);
 	GENODE_RPC_THROW(Rpc_map_buffer_ppgtt, bool, map_buffer_ppgtt,
-	                 GENODE_TYPE_LIST(Mapping_buffer_failed, Out_of_ram),
+	                 GENODE_TYPE_LIST(Mapping_buffer_failed, Out_of_caps, Out_of_ram),
 	                 Gpu::Buffer_id, Gpu::addr_t);
 	GENODE_RPC(Rpc_unmap_buffer_ppgtt, void, unmap_buffer_ppgtt,
 	           Gpu::Buffer_id, Gpu::addr_t);