diff --git a/include/mapnik/text/scrptrun.hpp b/include/mapnik/text/scrptrun.hpp
index 7cee74197..d7e7b0bf6 100644
--- a/include/mapnik/text/scrptrun.hpp
+++ b/include/mapnik/text/scrptrun.hpp
@@ -23,9 +23,9 @@
 #include <unicode/uobject.h>
 #include <unicode/uscript.h>
 #pragma GCC diagnostic pop
+#include <vector>
 
 const unsigned int STACK_SIZE = 1 << 7; // 2^n
-const unsigned int STACK_MASK = STACK_SIZE - 1;
 
 struct ScriptRecord
 {
@@ -36,6 +36,8 @@ struct ScriptRecord
 
 struct ParenStackEntry
 {
+    ParenStackEntry(int32_t pairIndex_, UScriptCode scriptCode_)
+        : pairIndex(pairIndex_), scriptCode(scriptCode_) {}
     int32_t pairIndex = 0;
     UScriptCode scriptCode = USCRIPT_INVALID_CODE;
 };
@@ -88,7 +90,7 @@ private:
     int32_t scriptEnd;
     UScriptCode scriptCode;
 
-    ParenStackEntry parenStack[STACK_SIZE];
+    std::vector<ParenStackEntry> parenStack;
     int32_t parenSP;
 
     static int8_t highBit(int32_t value);
@@ -108,16 +110,19 @@ private:
 
 inline ScriptRun::ScriptRun()
 {
+    parenStack.reserve(STACK_SIZE);
     reset(nullptr, 0, 0);
 }
 
 inline ScriptRun::ScriptRun(const UChar chars[], int32_t length)
 {
+    parenStack.reserve(STACK_SIZE);
     reset(chars, 0, length);
 }
 
 inline ScriptRun::ScriptRun(const UChar chars[], int32_t start, int32_t length)
 {
+    parenStack.reserve(STACK_SIZE);
     reset(chars, start, length);
 }
 
diff --git a/src/text/scrptrun.cpp b/src/text/scrptrun.cpp
index 4dd25eb03..071b7b239 100644
--- a/src/text/scrptrun.cpp
+++ b/src/text/scrptrun.cpp
@@ -21,7 +21,6 @@
 #pragma GCC diagnostic pop
 
 #include <mapnik/text/scrptrun.hpp>
-#include <cstddef>
 
 template <class T, std::size_t N>
 constexpr std::size_t ARRAY_SIZE(const T (&array)[N]) noexcept
@@ -161,9 +160,8 @@ UBool ScriptRun::next()
         // characters above it on the stack will be poped.
         if (pairIndex >= 0) {
             if ((pairIndex & 1) == 0) {
-                parenSP = (parenSP + 1) & STACK_MASK; // avoid out-of-bounds access
-                parenStack[parenSP].pairIndex = pairIndex;
-                parenStack[parenSP].scriptCode  = scriptCode;
+                ++parenSP;
+                parenStack.emplace_back(pairIndex, scriptCode);
             } else if (parenSP >= 0) {
                 int32_t pi = pairIndex & ~1;