diff --git a/src/lib/sdl/audio/SDL_genodeaudio.cc b/src/lib/sdl/audio/SDL_genodeaudio.cc
index 699668c..2d50716 100644
--- a/src/lib/sdl/audio/SDL_genodeaudio.cc
+++ b/src/lib/sdl/audio/SDL_genodeaudio.cc
@@ -79,12 +79,10 @@ struct Volume_config
 
 		Genode::Xml_node config = _config_rom.xml();
 
-		try {
-			unsigned int config_volume;
-			config.sub_node("sdl_audio_volume").attribute("value")
-				.value(&config_volume);
-			volume = (float)config_volume / 100;
-		} catch (...) { }
+		config.with_sub_node("sdl_audio_volume", [&] (Genode::Xml_node const &node) {
+			volume = (float)node.attribute_value("value", (unsigned)(volume*100))
+			       / 100;
+		});
 
 		Genode::log("Change SDL audio volume to ", volume * 100);
 	}
diff --git a/src/lib/sdl/sdl_main.cc b/src/lib/sdl/sdl_main.cc
index 53a03cf..2b34dfc 100644
--- a/src/lib/sdl/sdl_main.cc
+++ b/src/lib/sdl/sdl_main.cc
@@ -74,14 +74,20 @@ void Libc::Component::construct(Libc::Env &env)
 		int arg_i = 0;
 		int env_i = 0;
 		node.for_each_sub_node([&] (Xml_node const &node) {
+
 			/* insert an argument */
 			if (node.has_type("arg")) try {
+
 				Xml_attribute attr = node.attribute("value");
+				attr.with_raw_value([&] (char const *start, size_t length) {
 
-				Genode::size_t const arg_len = attr.value_size()+1;
-				char *arg = argv[arg_i] = (char*)malloc(arg_len);
+					size_t const size = length + 1; /* for null termination */
+
+					argv[arg_i] = (char *)malloc(size);
+
+					Genode::copy_cstring(argv[arg_i], start, size);
+				});
 
-				attr.value(arg, arg_len);
 				++arg_i;
 
 			} catch (Xml_node::Nonexistent_sub_node) { }
@@ -90,22 +96,56 @@ void Libc::Component::construct(Libc::Env &env)
 
 			/* insert an environment variable */
 			if (node.has_type("env")) try {
-				Xml_attribute key_attr = node.attribute("key");
-				Xml_attribute val_attr = node.attribute("value");
 
-				Genode::size_t const pair_len =
-					key_attr.value_size() +
-					val_attr.value_size() + 1;
-				char *env = envp[env_i] = (char*)malloc(pair_len);
+				auto check_attr = [] (Xml_node node, auto key) {
+					if (!node.has_attribute(key))
+						Genode::warning("<env> node lacks '", key, "' attribute"); };
+
+				check_attr(node, "key");
+				check_attr(node, "value");
+
+				Xml_attribute const key   = node.attribute("key");
+				Xml_attribute const value = node.attribute("value");
+
+				using namespace Genode;
+
+				/*
+				 * An environment variable has the form <key>=<value>, followed
+				 * by a terminating zero.
+				 */
+				size_t const var_size = key  .value_size() + 1
+				                      + value.value_size() + 1;
+
+				envp[env_i] = (char*)malloc(var_size);
+
+				size_t pos = 0;
+
+				/* append characters to env variable with zero termination */
+				auto append = [&] (char const *s, size_t len) {
+
+					if (pos + len >= var_size) {
+						/* this should never happen */
+						warning("truncated environment variable: ", node);
+						return;
+					}
+
+					copy_cstring(envp[env_i] + pos, s, len + 1);
+					pos += len;
+				};
+
+				key.with_raw_value([&] (char const *start, size_t length) {
+					append(start, length); });
+
+				append("=", 1);
+
+				value.with_raw_value([&] (char const *start, size_t length) {
+					append(start, length); });
 
-				Genode::size_t off = 0;
-				key_attr.value(&env[off], key_attr.value_size()+1);
-				off = key_attr.value_size();
-				env[off++] = '=';
-				val_attr.value(&env[off], val_attr.value_size()+1);
 				++env_i;
 
-			} catch (Xml_node::Nonexistent_sub_node) { }
+			}
+			catch (Xml_node::Nonexistent_sub_node)  { }
+			catch (Xml_node::Nonexistent_attribute) { }
 		});
 
 		envp[env_i] = NULL;