diff --git a/repos/base/include/util/string.h b/repos/base/include/util/string.h
index 90f8587827..b5d69ba411 100644
--- a/repos/base/include/util/string.h
+++ b/repos/base/include/util/string.h
@@ -592,7 +592,7 @@ class Genode::String
 
 			void out_string(char const *str, size_t n) override
 			{
-				while (n-- > 0 && _capacity_left())
+				while (n-- > 0 && _capacity_left() && *str)
 					_append(*str++);
 			}
 		};
diff --git a/repos/base/run/log.run b/repos/base/run/log.run
index 2f5ed2fc3b..d70835805c 100644
--- a/repos/base/run/log.run
+++ b/repos/base/run/log.run
@@ -36,5 +36,6 @@ compare_output_to {
 [init -> test-log] negative hex char:  0xfe
 [init -> test-log] positive hex char:  0x02
 [init -> test-log] multiarg string:    "parent -> child.7"
+[init -> test-log] String(Hex(3)):     0x3
 [init -> test-log] Test done.
 }
diff --git a/repos/base/src/test/log/main.cc b/repos/base/src/test/log/main.cc
index 45dd6fd5f0..395fedd04c 100644
--- a/repos/base/src/test/log/main.cc
+++ b/repos/base/src/test/log/main.cc
@@ -30,5 +30,8 @@ void Component::construct(Genode::Env &env)
 	typedef String<128> Label;
 	log("multiarg string:    ", Label(Char('"'), "parent -> child.", 7, Char('"')));
 
+	String<32> hex(Hex(3));
+	log("String(Hex(3)):     ", hex);
+
 	log("Test done.");
 }