diff --git a/opt/object-sensitive-dce/SideEffectSummary.cpp b/opt/object-sensitive-dce/SideEffectSummary.cpp
index 3ce4543030..39ec8d0701 100644
--- a/opt/object-sensitive-dce/SideEffectSummary.cpp
+++ b/opt/object-sensitive-dce/SideEffectSummary.cpp
@@ -345,6 +345,7 @@ s_expr to_s_expr(const Summary& summary) {
   std::vector<s_expr> s_exprs;
   s_exprs.emplace_back(std::to_string(summary.effects));
   std::vector<s_expr> mod_param_s_exprs;
+  mod_param_s_exprs.reserve(summary.modified_params.size());
   for (auto idx : summary.modified_params) {
     mod_param_s_exprs.emplace_back(idx);
   }
diff --git a/opt/outliner/InstructionSequenceOutliner.cpp b/opt/outliner/InstructionSequenceOutliner.cpp
index 1da8f7e840..ed09d441dc 100644
--- a/opt/outliner/InstructionSequenceOutliner.cpp
+++ b/opt/outliner/InstructionSequenceOutliner.cpp
@@ -1738,6 +1738,7 @@ class OutlinedMethodCreator {
     auto manager = g_redex->get_position_pattern_switch_manager();
     // Order methods to make sure we get deterministic pattern-ids.
     std::vector<DexMethod*> ordered_methods;
+    ordered_methods.reserve(ci.methods.size());
     for (auto& p : ci.methods) {
       ordered_methods.push_back(p.first);
     }
diff --git a/opt/virtual_merging/VirtualMerging.cpp b/opt/virtual_merging/VirtualMerging.cpp
index 8d13972cb1..2c607f323d 100644
--- a/opt/virtual_merging/VirtualMerging.cpp
+++ b/opt/virtual_merging/VirtualMerging.cpp
@@ -1375,6 +1375,8 @@ void VirtualMerging::merge_methods(
 // Part 5: Remove methods within classes.
 void VirtualMerging::remove_methods() {
   std::vector<DexClass*> classes_with_virtual_methods_to_remove;
+  classes_with_virtual_methods_to_remove.reserve(
+      m_virtual_methods_to_remove.size());
   for (auto& p : m_virtual_methods_to_remove) {
     classes_with_virtual_methods_to_remove.push_back(p.first);
   }