diff --git a/CMakeLists.txt b/CMakeLists.txt
index df70d49..9a8534d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -94,6 +94,10 @@ endif()
 
 set(TEST_FLAGS -Wall -Wextra -Wpedantic -Wunreachable-code -UNDEBUG)
 
+if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+  list(APPEND TEST_FLAGS -Wno-gnu-anonymous-struct -Wno-nested-anon-types)
+endif()
+
 include(CTest)
 
 if(BUILD_TESTING)
diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index a99d920..3989160 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -239,9 +239,13 @@ struct Node {
   int8_t partialKeyLen = 0;
   int32_t numChildren = 0;
   Node *parent = nullptr;
-  uint8_t partialKey[kPartialKeyMaxLenEntryPresent];
-  // If not entryPresent, then the partial key might spill over into entry
-  Entry entry;
+  union {
+    uint8_t partialKey[kPartialKeyMaxLenEntryPresent + sizeof(Entry)];
+    struct {
+      uint8_t padding[kPartialKeyMaxLenEntryPresent];
+      Entry entry;
+    };
+  };
   /* end section that's copied to the next node */
 };
 
@@ -1536,8 +1540,13 @@ template <bool kBegin>
   for (;;) {
 
     if ((*self)->partialKeyLen > 0) {
+      const bool wouldBePresent =
+          key.size() <= kPartialKeyMaxLenEntryPresent + int(sizeof(Entry));
       // Handle an existing partial key
       int commonLen = std::min<int>((*self)->partialKeyLen, key.size());
+      if (wouldBePresent) {
+        commonLen = std::min(commonLen, kPartialKeyMaxLenEntryPresent);
+      }
       int partialKeyIndex = longestCommonPrefixPartialKey(
           (*self)->partialKey, key.data(), commonLen);
       if (partialKeyIndex < (*self)->partialKeyLen) {
diff --git a/Internal.h b/Internal.h
index 88635c3..020cfdd 100644
--- a/Internal.h
+++ b/Internal.h
@@ -549,14 +549,12 @@ template <class ConflictSetImpl> struct TestDriver {
         }
 #if DEBUG_VERBOSE && !defined(NDEBUG)
         if (writes[i].end.len == 0) {
-          fprintf(stderr, "Write: {%s} -> %d\n",
-                  printable(writes[i].begin).c_str(),
-                  int(writes[i].writeVersion));
+          fprintf(stderr, "Write: {%s} -> %" PRId64 "\n",
+                  printable(writes[i].begin).c_str(), writeVersion);
         } else {
-          fprintf(stderr, "Write: [%s, %s) -> %d\n",
+          fprintf(stderr, "Write: [%s, %s) -> %" PRId64 "\n",
                   printable(writes[i].begin).c_str(),
-                  printable(writes[i].end).c_str(),
-                  int(writes[i].writeVersion));
+                  printable(writes[i].end).c_str(), writeVersion);
         }
 #endif
       }