diff --git a/compiler2/union.c b/compiler2/union.c
index 66e03ed7df9aaae84ed93f76a20879483d4acd90..a578f32e8486ce3ea86f8da9c309e2fc27ada8e6 100644
--- a/compiler2/union.c
+++ b/compiler2/union.c
@@ -3216,12 +3216,14 @@ void defUnionTemplate(const struct_def *sdef, output_struct *output)
     "}\n"
     "if (template_selection == SPECIFIC_VALUE && "
     "single_value.union_selection == match_value.get_selection()) {\n"
+    "size_t previous_size = TTCN_Logger::get_logmatch_buffer_len();\n"
     "switch (single_value.union_selection) {\n", name, name);
   for (i = 0; i < sdef->nElements; i++) {
     src = mputprintf(src, "case %s_%s:\n"
     "if(TTCN_Logger::VERBOSITY_COMPACT == TTCN_Logger::get_matching_verbosity()){\n"
     "TTCN_Logger::log_logmatch_info(\".%s\");\n"
     "single_value.field_%s->log_match(match_value.%s%s(), legacy);\n"
+    "TTCN_Logger::set_logmatch_buffer_len(previous_size);\n"
     "} else {\n"
       "TTCN_Logger::log_event_str(\"{ %s := \");\n"
       "single_value.field_%s->log_match(match_value.%s%s(), legacy);\n"
diff --git a/regression_test/templateUnion/TtemplateUnion.ttcn b/regression_test/templateUnion/TtemplateUnion.ttcn
index 5ba09a28b5f5313c828dfcb60c208a308f3dcaa4..f71078785a7101c6af9ecc6d8b90f7dd501f21c6 100644
--- a/regression_test/templateUnion/TtemplateUnion.ttcn
+++ b/regression_test/templateUnion/TtemplateUnion.ttcn
@@ -200,6 +200,27 @@ testcase tc_record_withWildCard3E() runs on templateUnion_mycomp {
   if(ispresent(vtl_rec2.u.i)){setverdict(fail)}else {setverdict(pass)};
 }
 
+testcase tc_logmatch_cleanup() runs on templateUnion_mycomp {
+  // bug 567844
+  // When logging the result of an unsuccessful matching operation with a union template,
+  // the matching info is not properly cleaned up, and can cause future logged matchings
+  // of the same type to also display leftover data.
+  var charstring log2_exp := " matched";
+  for (var integer i := 0; i < 5; i := i + 1) {
+    var templateUnion_myunion x := { f1 := i };
+    var charstring log1 := log2str(match(x, templateUnion_myunion: { f1 := 10 }));
+    var charstring log1_exp := ".f1 := " & int2str(i) & " with 10 unmatched";
+    if (log1 != log1_exp) {
+      setverdict(fail, "log1: ", log1, ", expected: ", log1_exp);
+    }
+    var charstring log2 := log2str(match(x, templateUnion_myunion: { f1 := ? }));
+    if (log2 != log2_exp) {
+      setverdict(fail, "log2: ", log2, ", expected: ", log2_exp);
+    }
+  }
+  setverdict(pass);
+}
+
 control {
  execute(templateUnionSpec());
  execute(templateUnionList());
@@ -209,5 +230,6 @@ control {
  execute(templateUnionAnyorNone());
 // execute(templateUnionIfpresent());
  execute(tc_record_withWildCard3E());
+ execute(tc_logmatch_cleanup());
 }
 }