diff --git a/src/test/vector.cpp b/src/test/vector.cpp
index 0bc2aeb362..a206b278ef 100644
--- a/src/test/vector.cpp
+++ b/src/test/vector.cpp
@@ -19,6 +19,7 @@ Revision History:
 #include "util/vector.h"
 #include "util/rational.h"
 #include <iostream>
+#include <cstdint>
 
 static void tst_resize_rational() {
     // grow from empty using default initialization (zero)
@@ -141,8 +142,16 @@ static void tst1() {
     }
 }
 
+static void tst_expand_vector_byte_count() {
+    vector<uint16_t, true, uint8_t> v;
+    for (unsigned i = 0; i < 192; ++i)
+        v.push_back(i);
+    ENSURE(v.size() == 192);
+}
+
 void tst_vector() {
     tst_resize_rational();
     tst_resize();
     tst1();
+    tst_expand_vector_byte_count();
 }
diff --git a/src/util/vector.h b/src/util/vector.h
index 41f81fc953..6ccda5adc7 100644
--- a/src/util/vector.h
+++ b/src/util/vector.h
@@ -80,9 +80,9 @@ class vector {
             static_assert(std::is_nothrow_move_constructible<T>::value);
             SASSERT(capacity() > 0);
             SZ old_capacity = reinterpret_cast<SZ *>(m_data)[CAPACITY_IDX];
-            SZ old_capacity_T = sizeof(T) * old_capacity + sizeof(SZ) * 2;
+            size_t old_capacity_T = sizeof(T) * static_cast<size_t>(old_capacity) + sizeof(SZ) * 2;
             SZ new_capacity = (3 * old_capacity + 1) >> 1;
-            SZ new_capacity_T = sizeof(T) * new_capacity + sizeof(SZ) * 2;
+            size_t new_capacity_T = sizeof(T) * static_cast<size_t>(new_capacity) + sizeof(SZ) * 2;
             if (new_capacity <= old_capacity || new_capacity_T <= old_capacity_T) {
                 throw default_exception("Overflow encountered when expanding vector");
             }