diff --git a/cpp/ql/test/library-tests/regex/parse.expected b/cpp/ql/test/library-tests/regex/parse.expected
index b2f12c744a0..b7d2e50a062 100644
--- a/cpp/ql/test/library-tests/regex/parse.expected
+++ b/cpp/ql/test/library-tests/regex/parse.expected
@@ -26,6 +26,12 @@
 
 #-----| [RegExpConstant, RegExpNormalChar] b
 
+#-----| [RegExpConstant, RegExpNormalChar] \
+
+#-----| [RegExpConstant, RegExpNormalChar] 0
+
+#-----| [RegExpConstant, RegExpNormalChar] \0
+
 #-----| [RegExpConstant, RegExpEscape] \cZ
 
 #-----| [RegExpConstant, RegExpEscape] \cA
@@ -283,6 +289,10 @@
 #-----| 0 -> [RegExpConstant, RegExpNormalChar] 0
 #-----| 1 -> [RegExpConstant, RegExpNormalChar] 9
 
+#-----| [RegExpCharacterClass] [\0]
+#-----| 0 -> [RegExpConstant, RegExpNormalChar] \
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] 0
+
 #-----| [RegExpCharacterClass] [\cZ]
 #-----| 0 -> [RegExpConstant, RegExpEscape] \cZ
 
diff --git a/cpp/ql/test/library-tests/regex/regexp.cpp b/cpp/ql/test/library-tests/regex/regexp.cpp
index 86352695dc5..18c3b8d3e48 100644
--- a/cpp/ql/test/library-tests/regex/regexp.cpp
+++ b/cpp/ql/test/library-tests/regex/regexp.cpp
@@ -80,6 +80,10 @@ std::regex r_uni("\\u{9879}");
 std::regex r_ctrl1("\\cA");
 std::regex r_ctrl2("[\\cZ]");
 
+// NUL escape
+std::regex r_nul1("\\0");
+std::regex r_nul2("[\\0]");
+
 // String literal spellings for location tests
 std::regex r_loc_plain("a\\nb");
 std::basic_regex<wchar_t> r_loc_L(L"abc");
diff --git a/cpp/ql/test/library-tests/regex/regexp.expected b/cpp/ql/test/library-tests/regex/regexp.expected
index 0a5cfb87b6b..b2c734087d6 100644
--- a/cpp/ql/test/library-tests/regex/regexp.expected
+++ b/cpp/ql/test/library-tests/regex/regexp.expected
@@ -6,6 +6,7 @@ groupNumber
 | file://:0:0:0:0 | (o\|b) | 1 |
 term
 | file://:0:0:0:0 | 0 | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | 0 | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | 0-9 | RegExpCharacterRange |
 | file://:0:0:0:0 | 1 | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | 2 | RegExpConstant,RegExpNormalChar |
@@ -48,6 +49,7 @@ term
 | file://:0:0:0:0 | [[:digit:]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [[a-f] | RegExpCharacterClass |
 | file://:0:0:0:0 | [[a-f]A-F] | RegExpSequence |
+| file://:0:0:0:0 | [\\0] | RegExpCharacterClass |
 | file://:0:0:0:0 | [\\cZ] | RegExpCharacterClass |
 | file://:0:0:0:0 | [\\w] | RegExpCharacterClass |
 | file://:0:0:0:0 | [\\w]+ | RegExpPlus |
@@ -58,6 +60,8 @@ term
 | file://:0:0:0:0 | [^]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [a-fA-F0-9_] | RegExpCharacterClass |
 | file://:0:0:0:0 | [abc] | RegExpCharacterClass |
+| file://:0:0:0:0 | \\ | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | \\0 | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | \\1 | RegExpBackRef |
 | file://:0:0:0:0 | \\B | RegExpNonWordBoundary |
 | file://:0:0:0:0 | \\D | RegExpCharacterClassEscape |
@@ -154,6 +158,7 @@ term
 | file://:0:0:0:0 | o\|b | RegExpAlt |
 regExpNormalCharValue
 | file://:0:0:0:0 | 0 | 0 |
+| file://:0:0:0:0 | 0 | 0 |
 | file://:0:0:0:0 | 1 | 1 |
 | file://:0:0:0:0 | 2 | 2 |
 | file://:0:0:0:0 | 3 | 3 |
@@ -169,6 +174,8 @@ regExpNormalCharValue
 | file://:0:0:0:0 | F | F |
 | file://:0:0:0:0 | Z | Z |
 | file://:0:0:0:0 | [ | [ |
+| file://:0:0:0:0 | \\ | \\ |
+| file://:0:0:0:0 | \\0 | \\0 |
 | file://:0:0:0:0 | \\D | D |
 | file://:0:0:0:0 | \\S | S |
 | file://:0:0:0:0 | \\W | W |