diff --git a/js/src/jit/CodeGenerator.cpp b/js/src/jit/CodeGenerator.cpp
index 74754635d546..658b6eba5ebe 100644
--- a/js/src/jit/CodeGenerator.cpp
+++ b/js/src/jit/CodeGenerator.cpp
@@ -2114,12 +2114,11 @@ static bool PrepareAndExecuteRegExp(JSContext* cx, MacroAssembler& masm,
   }
 
   // Don't handle RegExps with excessive parens.
-  masm.load32(Address(temp1, RegExpShared::offsetOfParenCount()), temp2);
-  masm.branch32(Assembler::AboveOrEqual, temp2,
+  masm.load32(Address(temp1, RegExpShared::offsetOfPairCount()), temp2);
+  masm.branch32(Assembler::Above, temp2,
                 Imm32(RegExpObject::MaxPairCount), failure);
 
   // Fill in the paren count in the MatchPairs on the stack.
-  masm.add32(Imm32(1), temp2);
   masm.store32(temp2, pairCountAddress);
 
   // Load the code pointer for the type of input string we have, and compute
diff --git a/js/src/vm/RegExpObject.cpp b/js/src/vm/RegExpObject.cpp
index 43323e273882..534c6d158c2c 100644
--- a/js/src/vm/RegExpObject.cpp
+++ b/js/src/vm/RegExpObject.cpp
@@ -946,7 +946,7 @@ bool js::StringHasRegExpMetaChars(JSLinearString* str) {
 /* RegExpShared */
 
 RegExpShared::RegExpShared(JSAtom* source, RegExpFlags flags)
-    : headerAndSource(source), parenCount(0), flags(flags) {}
+    : headerAndSource(source), pairCount_(0), flags(flags) {}
 
 void RegExpShared::traceChildren(JSTracer* trc) {
   // Discard code to avoid holding onto ExecutablePools.
@@ -1057,7 +1057,7 @@ void RegExpShared::useAtomMatch(HandleAtom pattern) {
   MOZ_ASSERT(kind() == RegExpShared::Kind::Unparsed);
   kind_ = RegExpShared::Kind::Atom;
   patternAtom_ = pattern;
-  parenCount = 0;
+  pairCount_ = 1;
 }
 
 #else   // !ENABLE_NEW_REGEXP
@@ -1082,7 +1082,8 @@ bool RegExpShared::compile(JSContext* cx, MutableHandleRegExpShared re,
     return false;
   }
 
-  re->parenCount = data.capture_count;
+  // Add one to account for the whole-match capture.
+  re->pairCount_ = data.capture_count + 1;
 
   JitCodeTables tables;
   irregexp::RegExpCode code = irregexp::CompilePattern(
diff --git a/js/src/vm/RegExpShared.h b/js/src/vm/RegExpShared.h
index 3f711d5340fd..f49153bf5f7c 100644
--- a/js/src/vm/RegExpShared.h
+++ b/js/src/vm/RegExpShared.h
@@ -102,7 +102,7 @@ class RegExpShared : public gc::TenuredCell {
 
   RegExpCompilation compilationArray[2];
 
-  uint32_t parenCount;
+  uint32_t pairCount_;
   JS::RegExpFlags flags;
 
 #ifdef ENABLE_NEW_REGEXP
@@ -156,13 +156,13 @@ class RegExpShared : public gc::TenuredCell {
 
   /* Accessors */
 
-  size_t getParenCount() const {
+  size_t pairCount() const {
 #ifdef ENABLE_NEW_REGEXP
     MOZ_ASSERT(kind() != Kind::Unparsed);
 #else
     MOZ_ASSERT(isCompiled());
 #endif
-    return parenCount;
+    return pairCount_;
   }
 
 #ifdef ENABLE_NEW_REGEXP
@@ -172,8 +172,6 @@ class RegExpShared : public gc::TenuredCell {
   void useAtomMatch(HandleAtom pattern);
 #endif
 
-  /* Accounts for the "0" (whole match) pair. */
-  size_t pairCount() const { return getParenCount() + 1; }
 
   JSAtom* getSource() const { return headerAndSource.ptr(); }
 
@@ -209,8 +207,8 @@ class RegExpShared : public gc::TenuredCell {
 
   static size_t offsetOfFlags() { return offsetof(RegExpShared, flags); }
 
-  static size_t offsetOfParenCount() {
-    return offsetof(RegExpShared, parenCount);
+  static size_t offsetOfPairCount() {
+    return offsetof(RegExpShared, pairCount_);
   }
 
   static size_t offsetOfJitCode(bool latin1) {