diff --git a/src/Reporter.cc b/src/Reporter.cc
index 4a8e35e650..053d6370d7 100644
--- a/src/Reporter.cc
+++ b/src/Reporter.cc
@@ -302,7 +302,7 @@ void Reporter::DoLog(const char* prefix, EventHandlerPtr event, FILE* out, Conne
 		s += buffer;
 		s += "\n";
 
-		fprintf(out, s.c_str());
+		fprintf(out, "%s", s.c_str());
 		}
 
 	if ( alloced )
diff --git a/testing/btest/Baseline/core.reporter-fmt-strings/output b/testing/btest/Baseline/core.reporter-fmt-strings/output
new file mode 100644
index 0000000000..10a883cb5d
--- /dev/null
+++ b/testing/btest/Baseline/core.reporter-fmt-strings/output
@@ -0,0 +1 @@
+error in /Users/jsiwek/tmp/bro/testing/btest/.tmp/core.reporter-fmt-strings/reporter-fmt-strings.bro, line 9: not an event (dont_interpret_this(%s))
diff --git a/testing/btest/core/reporter-fmt-strings.bro b/testing/btest/core/reporter-fmt-strings.bro
new file mode 100644
index 0000000000..0e0be77844
--- /dev/null
+++ b/testing/btest/core/reporter-fmt-strings.bro
@@ -0,0 +1,10 @@
+# The format string below should end up as a literal part of the reporter's
+# error message to stderr and shouldn't be replaced internally.
+#
+# @TEST-EXEC-FAIL: bro %INPUT >output 2>&1
+# @TEST-EXEC:      TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff output
+
+event bro_init()
+{
+    event dont_interpret_this("%s");
+}