diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 555e65e..02216ce 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -2148,7 +2148,7 @@ bool checkMaxBetweenExclusiveImpl(Node *n, int begin, int end,
     if (!mask) {
       return true;
     }
-    auto *child = self->children[__builtin_ctz(mask)];
+    auto *child = self->children[std::countr_zero(mask)];
     const bool firstRangeOk =
         !child->entryPresent || child->entry.rangeVersion <= readVersion;
     uint32_t compared = 0;
@@ -2183,7 +2183,7 @@ bool checkMaxBetweenExclusiveImpl(Node *n, int begin, int end,
     if (!mask) {
       return true;
     }
-    auto *child = self->children[__builtin_ctzll(mask) >> 2];
+    auto *child = self->children[std::countr_zero(mask) >> 2];
     const bool firstRangeOk =
         !child->entryPresent || child->entry.rangeVersion <= readVersion;
 
@@ -2223,7 +2223,7 @@ bool checkMaxBetweenExclusiveImpl(Node *n, int begin, int end,
     if (!mask) {
       return true;
     }
-    auto *child = self->children[__builtin_ctz(mask)];
+    auto *child = self->children[std::countr_zero(mask)];
     const bool firstRangeOk =
         !child->entryPresent || child->entry.rangeVersion <= readVersion;
 
@@ -2254,7 +2254,7 @@ bool checkMaxBetweenExclusiveImpl(Node *n, int begin, int end,
     if (!mask) {
       return true;
     }
-    auto *child = self->children[__builtin_ctz(mask)];
+    auto *child = self->children[std::countr_zero(mask)];
     const bool firstRangeOk =
         !child->entryPresent || child->entry.rangeVersion <= readVersion;
     uint32_t compared = 0;