diff --git a/binaryurp/source/unmarshal.cxx b/binaryurp/source/unmarshal.cxx
index d307c81cc0b5..4263edf8c91c 100644
--- a/binaryurp/source/unmarshal.cxx
+++ b/binaryurp/source/unmarshal.cxx
@@ -437,6 +437,7 @@ BinaryAny Unmarshal::readSequence(css::uno::TypeDescription const & type) {
         return BinaryAny(type, &p);
     }
     std::vector< BinaryAny > as;
+    as.reserve(n);
     for (sal_uInt32 i = 0; i != n; ++i) {
         as.push_back(readValue(ctd));
     }
@@ -477,6 +478,7 @@ void Unmarshal::readMemberValues(
             css::uno::TypeDescription(&ctd->pBaseTypeDescription->aBase),
             values);
     }
+    values->reserve(values->size() + ctd->nMembers);
     for (sal_Int32 i = 0; i != ctd->nMembers; ++i) {
         values->push_back(
             readValue(css::uno::TypeDescription(ctd->ppTypeRefs[i])));