diff --git a/engine/googletest_list.cpp b/engine/googletest_list.cpp
index f56d8701..196413bc 100644
--- a/engine/googletest_list.cpp
+++ b/engine/googletest_list.cpp
@@ -51,24 +51,23 @@ const std::string name_expr = "([[:alpha:][:digit:]_]+[[:alpha:][:digit:]_/]*)";
 /// The separator between a test suite and a test case.
 const std::string testsuite_testcase_separator = ".";
 
-/// A complete regular expression representing a line with a test suite
-/// definition, e,g.,
-/// * "TestSuite."
-/// * "TestSuite/Prefix.", or
-/// * "TestSuite/Prefix.    # TypeParam = .+"
-const std::string testsuite_expr =
-    name_expr + "\\.([[:space:]]+# TypeParam = .+)?";
-
 /// A complete regular expression representing a line with a test case
 /// definition, e,g.,
 /// * "  TestCase"
 /// * "  TestCase/0"
 /// * "  TestCase/0  # GetParam() = 4"
-const std::string testcase_expr =
-    "  " + name_expr + "([[:space:]]+# GetParam\\(\\) = .+)?";
+const std::regex testcase_re(
+    "  " + name_expr + "([[:space:]]+# GetParam\\(\\) = .+)?"
+);
 
-const std::regex testcase_re(testcase_expr);
-const std::regex testsuite_re(testsuite_expr);
+/// A complete regular expression representing a line with a test suite
+/// definition, e,g.,
+/// * "TestSuite."
+/// * "TestSuite/Prefix.", or
+/// * "TestSuite/Prefix.    # TypeParam = .+"
+const std::regex testsuite_re(
+    name_expr + "\\.([[:space:]]+# TypeParam = .+)?"
+);
 
 }  // anonymous namespace
 
diff --git a/engine/googletest_result.cpp b/engine/googletest_result.cpp
index e1bb3297..ea02d80a 100644
--- a/engine/googletest_result.cpp
+++ b/engine/googletest_result.cpp
@@ -53,12 +53,23 @@ using utils::optional;
 
 namespace {
 
+/// Internal string for specifying invalid output.
 const std::string invalid_output_message = "invalid output";
-const std::regex disabled_re(R"RE((YOU HAVE [[:digit:]]+ DISABLED TESTS?))RE");
+
+/// Regular expression for disabled tests line.
+const std::regex disabled_re(
+    R"RE((YOU HAVE [[:digit:]]+ DISABLED TESTS?))RE"
+);
+
+/// Regular expression for starting sentinel of results block.
 const std::regex starting_sentinel_re(
-    R"(\[[[:space:]]+RUN[[:space:]]+\][[:space:]]+[A-Za-z0-9]+\.[A-Za-z0-9]+)");
+    R"(\[[[:space:]]+RUN[[:space:]]+\][[:space:]]+[A-Za-z0-9]+\.[A-Za-z0-9]+)"
+);
+
+/// Regular expression for ending sentinel of results block.
 const std::regex ending_sentinel_re(
-    R"RE(\[[[:space:]]+(FAILED|OK|SKIPPED)[[:space:]]+\])RE");
+    R"RE(\[[[:space:]]+(FAILED|OK|SKIPPED)[[:space:]]+\])RE"
+);
 
 /// Parses a test result that does not accept a reason.
 ///