diff --git a/src/dwarfs/inode_manager.cpp b/src/dwarfs/inode_manager.cpp
index 5a5bfec6..5fbb6acd 100644
--- a/src/dwarfs/inode_manager.cpp
+++ b/src/dwarfs/inode_manager.cpp
@@ -458,7 +458,7 @@ class inode_ : public inode {
   static constexpr uint32_t const kNumIsValid{UINT32_C(1) << 0};
 
   uint32_t flags_{0};
-  uint32_t num_;
+  uint32_t num_{0};
   inode_fragments fragments_;
   files_vector files_;
 
diff --git a/src/dwarfs/nilsimsa.cpp b/src/dwarfs/nilsimsa.cpp
index ae766489..9406ce55 100644
--- a/src/dwarfs/nilsimsa.cpp
+++ b/src/dwarfs/nilsimsa.cpp
@@ -59,7 +59,7 @@ constexpr inline uint8_t tran3(uint8_t a, uint8_t b, uint8_t c, uint8_t n) {
 
 class nilsimsa::impl {
  public:
-  impl() { acc_.fill(0); }
+  impl() = default;
 
   void update(uint8_t const* data, size_t size) {
     if (size_ < 4) [[unlikely]] {
@@ -172,8 +172,8 @@ class nilsimsa::impl {
     size_ += size;
   }
 
-  std::array<size_t, 256> acc_;
-  std::array<uint8_t, 4> w_;
+  std::array<size_t, 256> acc_{};
+  std::array<uint8_t, 4> w_{};
   size_t size_{0};
 };
 
diff --git a/test/block_merger_test.cpp b/test/block_merger_test.cpp
index 2bed1dc5..e06eb04b 100644
--- a/test/block_merger_test.cpp
+++ b/test/block_merger_test.cpp
@@ -84,9 +84,9 @@ struct sized_block {
     return os << source_id << "." << index << " (" << size << ")";
   }
 
-  size_t source_id;
-  size_t index;
-  size_t size;
+  size_t source_id{0};
+  size_t index{0};
+  size_t size{0};
 };
 
 class sized_block_merger_policy {