diff --git a/cpp/ql/test/library-tests/regex/parse.expected b/cpp/ql/test/library-tests/regex/parse.expected
index e2897718244..32bf025e6d7 100644
--- a/cpp/ql/test/library-tests/regex/parse.expected
+++ b/cpp/ql/test/library-tests/regex/parse.expected
@@ -42,6 +42,32 @@
 
 #-----| [RegExpConstant, RegExpNormalChar] [
 
+#-----| [RegExpConstant, RegExpNormalChar] [
+
+#-----| [RegExpConstant, RegExpNormalChar] =
+
+#-----| [RegExpConstant, RegExpNormalChar] b
+
+#-----| [RegExpConstant, RegExpNormalChar] =
+
+#-----| [RegExpConstant, RegExpNormalChar] ]a-f]
+
+#-----| [RegExpConstant, RegExpNormalChar] [
+
+#-----| [RegExpConstant, RegExpNormalChar] =
+
+#-----| [RegExpConstant, RegExpNormalChar] a
+
+#-----| [RegExpConstant, RegExpNormalChar] =
+
+#-----| [RegExpConstant, RegExpNormalChar] ]
+
+#-----| [RegExpConstant, RegExpNormalChar] A
+
+#-----| [RegExpConstant, RegExpNormalChar] F
+
+#-----| [RegExpConstant, RegExpNormalChar] [
+
 #-----| [RegExpConstant, RegExpNormalChar] a-f]
 
 #-----| [RegExpConstant, RegExpNormalChar] A
@@ -179,6 +205,14 @@
 #-----| 1 -> [RegExpConstant, RegExpEscape] \n
 #-----| 2 -> [RegExpConstant, RegExpNormalChar] b
 
+#-----| [RegExpSequence] [A-F[[=b=]]a-f]
+#-----| 0 -> [RegExpCharacterClass] [A-F[[=b=]
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] ]a-f]
+
+#-----| [RegExpSequence] [[=a=]]
+#-----| 0 -> [RegExpCharacterClass] [[=a=]
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] ]
+
 #-----| [RegExpSequence] [A-F[[.b.]]a-f]
 #-----| 0 -> [RegExpCharacterClass] [A-F[[.b.]]
 #-----| 1 -> [RegExpConstant, RegExpNormalChar] a-f]
@@ -283,6 +317,10 @@
 #-----| 0 -> [RegExpConstant, RegExpNormalChar] A
 #-----| 1 -> [RegExpConstant, RegExpNormalChar] F
 
+#-----| [RegExpCharacterRange] A-F
+#-----| 0 -> [RegExpConstant, RegExpNormalChar] A
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] F
+
 #-----| [RegExpCharacterRange] a-f
 #-----| 0 -> [RegExpConstant, RegExpNormalChar] a
 #-----| 1 -> [RegExpConstant, RegExpNormalChar] f
@@ -313,6 +351,20 @@
 #-----| [RegExpCharacterClass] [\cZ]
 #-----| 0 -> [RegExpConstant, RegExpEscape] \cZ
 
+#-----| [RegExpCharacterClass] [A-F[[=b=]
+#-----| 0 -> [RegExpCharacterRange] A-F
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] [
+#-----| 2 -> [RegExpConstant, RegExpNormalChar] [
+#-----| 3 -> [RegExpConstant, RegExpNormalChar] =
+#-----| 4 -> [RegExpConstant, RegExpNormalChar] b
+#-----| 5 -> [RegExpConstant, RegExpNormalChar] =
+
+#-----| [RegExpCharacterClass] [[=a=]
+#-----| 0 -> [RegExpConstant, RegExpNormalChar] [
+#-----| 1 -> [RegExpConstant, RegExpNormalChar] =
+#-----| 2 -> [RegExpConstant, RegExpNormalChar] a
+#-----| 3 -> [RegExpConstant, RegExpNormalChar] =
+
 #-----| [RegExpCharacterClass] [A-F[[.b.]]
 #-----| 0 -> [RegExpCharacterRange] A-F
 #-----| 1 -> [RegExpConstant, RegExpNormalChar] [
diff --git a/cpp/ql/test/library-tests/regex/regexp.cpp b/cpp/ql/test/library-tests/regex/regexp.cpp
index ebf3b49367f..8806b654807 100644
--- a/cpp/ql/test/library-tests/regex/regexp.cpp
+++ b/cpp/ql/test/library-tests/regex/regexp.cpp
@@ -74,6 +74,10 @@ std::regex r_posix3("[A-F[:digit:]a-f]");
 std::regex r_posix_coll1("[[.a.]]");
 std::regex r_posix_coll2("[A-F[[.b.]]a-f]");
 
+// POSIX equivalence classes
+std::regex r_posix_equiv1("[[=a=]]");
+std::regex r_posix_equiv2("[A-F[[=b=]]a-f]");
+
 // *Not* a POSIX bracket expression; just a regular character class.
 std::regex r_posix4("[:digit:]");
 
diff --git a/cpp/ql/test/library-tests/regex/regexp.expected b/cpp/ql/test/library-tests/regex/regexp.expected
index 9c7f8506d32..b8c4976a0df 100644
--- a/cpp/ql/test/library-tests/regex/regexp.expected
+++ b/cpp/ql/test/library-tests/regex/regexp.expected
@@ -29,10 +29,16 @@ term
 | file://:0:0:0:0 | .* | RegExpStar |
 | file://:0:0:0:0 | : | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | :+ | RegExpPlus |
+| file://:0:0:0:0 | = | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | = | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | = | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | = | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | A | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | A | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | A | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | A | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | A | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | A-F | RegExpCharacterRange |
 | file://:0:0:0:0 | A-F | RegExpCharacterRange |
 | file://:0:0:0:0 | A-F | RegExpCharacterRange |
 | file://:0:0:0:0 | A-F | RegExpCharacterRange |
@@ -41,20 +47,28 @@ term
 | file://:0:0:0:0 | F | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | F | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | F | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | F | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | Z | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | [ | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | [ | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | [ | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | [ | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | [ | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | [123] | RegExpCharacterClass |
 | file://:0:0:0:0 | [.a.] | RegExpPosixCollatingSymbol |
 | file://:0:0:0:0 | [.b.] | RegExpPosixCollatingSymbol |
 | file://:0:0:0:0 | [A-F[:digit:]a-f] | RegExpCharacterClass |
 | file://:0:0:0:0 | [A-F[[.b.]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [A-F[[.b.]]a-f] | RegExpSequence |
+| file://:0:0:0:0 | [A-F[[=b=] | RegExpCharacterClass |
+| file://:0:0:0:0 | [A-F[[=b=]]a-f] | RegExpSequence |
 | file://:0:0:0:0 | [[.a.]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [[:alpha:][:digit:]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [[:alpha:]] | RegExpCharacterClass |
 | file://:0:0:0:0 | [[:alpha:]][[:digit:]] | RegExpSequence |
 | file://:0:0:0:0 | [[:digit:]] | RegExpCharacterClass |
+| file://:0:0:0:0 | [[=a=] | RegExpCharacterClass |
+| file://:0:0:0:0 | [[=a=]] | RegExpSequence |
 | 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 |
@@ -100,6 +114,8 @@ term
 | file://:0:0:0:0 | \| | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | ] | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | ] | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | ] | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | ]a-f] | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | _ | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
@@ -113,6 +129,7 @@ term
 | file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | a | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | a* | RegExpStar |
 | file://:0:0:0:0 | a*b+c?d | RegExpSequence |
 | file://:0:0:0:0 | a+ | RegExpPlus |
@@ -145,6 +162,7 @@ term
 | file://:0:0:0:0 | b | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | b | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | b | RegExpConstant,RegExpNormalChar |
+| file://:0:0:0:0 | b | RegExpConstant,RegExpNormalChar |
 | file://:0:0:0:0 | b+ | RegExpPlus |
 | file://:0:0:0:0 | b+ | RegExpPlus |
 | file://:0:0:0:0 | bar | RegExpConstant,RegExpNormalChar |
@@ -174,6 +192,11 @@ regExpNormalCharValue
 | file://:0:0:0:0 | !a | !a |
 | file://:0:0:0:0 | - | - |
 | file://:0:0:0:0 | : | : |
+| file://:0:0:0:0 | = | = |
+| file://:0:0:0:0 | = | = |
+| file://:0:0:0:0 | = | = |
+| file://:0:0:0:0 | = | = |
+| file://:0:0:0:0 | A | A |
 | file://:0:0:0:0 | A | A |
 | file://:0:0:0:0 | A | A |
 | file://:0:0:0:0 | A | A |
@@ -182,9 +205,13 @@ regExpNormalCharValue
 | file://:0:0:0:0 | F | F |
 | file://:0:0:0:0 | F | F |
 | file://:0:0:0:0 | F | F |
+| 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 | [ | [ |
+| file://:0:0:0:0 | [ | [ |
+| file://:0:0:0:0 | [ | [ |
 | file://:0:0:0:0 | \\0 | 0 |
 | file://:0:0:0:0 | \\0 | 0 |
 | file://:0:0:0:0 | \\D | D |
@@ -207,6 +234,8 @@ regExpNormalCharValue
 | file://:0:0:0:0 | \| | \| |
 | file://:0:0:0:0 | ] | ] |
 | file://:0:0:0:0 | ] | ] |
+| file://:0:0:0:0 | ] | ] |
+| file://:0:0:0:0 | ]a-f] | ]a-f] |
 | file://:0:0:0:0 | _ | _ |
 | file://:0:0:0:0 | a | a |
 | file://:0:0:0:0 | a | a |
@@ -220,6 +249,7 @@ regExpNormalCharValue
 | file://:0:0:0:0 | a | a |
 | file://:0:0:0:0 | a | a |
 | file://:0:0:0:0 | a | a |
+| file://:0:0:0:0 | a | a |
 | file://:0:0:0:0 | a-f] | a-f] |
 | file://:0:0:0:0 | abc | abc |
 | file://:0:0:0:0 | abc | abc |
@@ -240,6 +270,7 @@ regExpNormalCharValue
 | file://:0:0:0:0 | b | b |
 | file://:0:0:0:0 | b | b |
 | file://:0:0:0:0 | b | b |
+| file://:0:0:0:0 | b | b |
 | file://:0:0:0:0 | bar | bar |
 | file://:0:0:0:0 | bar | bar |
 | file://:0:0:0:0 | c | c |