diff --git a/src/corelib/tools/qchar.cpp b/src/corelib/tools/qchar.cpp
index ff17a52a75..d99bba93ee 100644
--- a/src/corelib/tools/qchar.cpp
+++ b/src/corelib/tools/qchar.cpp
@@ -1680,6 +1680,8 @@ struct UCS2Pair {
     ushort u2;
 };
 
+inline bool operator<(const UCS2Pair &ligature1, const UCS2Pair &ligature2)
+{ return ligature1.u1 < ligature2.u1; }
 inline bool operator<(ushort u1, const UCS2Pair &ligature)
 { return u1 < ligature.u1; }
 inline bool operator<(const UCS2Pair &ligature, ushort u1)
@@ -1690,6 +1692,8 @@ struct UCS2SurrogatePair {
     UCS2Pair p2;
 };
 
+inline bool operator<(const UCS2SurrogatePair &ligature1, const UCS2SurrogatePair &ligature2)
+{ return QChar::surrogateToUcs4(ligature1.p1.u1, ligature1.p1.u2) < QChar::surrogateToUcs4(ligature2.p1.u1, ligature2.p1.u2); }
 inline bool operator<(uint u1, const UCS2SurrogatePair &ligature)
 { return u1 < QChar::surrogateToUcs4(ligature.p1.u1, ligature.p1.u2); }
 inline bool operator<(const UCS2SurrogatePair &ligature, uint u1)
diff --git a/src/corelib/tools/qregexp.cpp b/src/corelib/tools/qregexp.cpp
index c0cd419c53..ef2dba5700 100644
--- a/src/corelib/tools/qregexp.cpp
+++ b/src/corelib/tools/qregexp.cpp
@@ -2883,6 +2883,8 @@ static const struct CategoriesRangeMapEntry {
     { "YijingHexagramSymbols",                0x4DC0, 0x4DFF }
 };
 
+inline bool operator<(const CategoriesRangeMapEntry &entry1, const CategoriesRangeMapEntry &entry2)
+{ return qstrcmp(entry1.name, entry2.name) < 0; }
 inline bool operator<(const char *name, const CategoriesRangeMapEntry &entry)
 { return qstrcmp(name, entry.name) < 0; }
 inline bool operator<(const CategoriesRangeMapEntry &entry, const char *name)