diff --git a/.gitignore b/.gitignore
index 8104503a8..e7979fbdc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -115,3 +115,5 @@ genaisrc/genblogpost.genai.mts
 *.mts
 # Bazel generated files
 bazel-*
+# Test binaries
+test_translate_race
diff --git a/src/ast/ast.cpp b/src/ast/ast.cpp
index 6e2f2e6af..a6d65d098 100644
--- a/src/ast/ast.cpp
+++ b/src/ast/ast.cpp
@@ -1316,7 +1316,15 @@ ast_manager::ast_manager(ast_manager const & src, bool disable_proofs):
 }
 
 void ast_manager::update_fresh_id(ast_manager const& m) {
-    m_fresh_id = std::max(m_fresh_id, m.m_fresh_id);
+    unsigned other_id = m.m_fresh_id.load(std::memory_order_relaxed);
+    unsigned current_id = m_fresh_id.load(std::memory_order_relaxed);
+    while (other_id > current_id) {
+        if (m_fresh_id.compare_exchange_weak(current_id, other_id, 
+                                              std::memory_order_relaxed,
+                                              std::memory_order_relaxed)) {
+            break;
+        }
+    }
 }
 
 
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 9dd564206..bab25c075 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -48,6 +48,7 @@ Revision History:
 #include "util/dependency.h"
 #include "util/rlimit.h"
 #include <variant>
+#include <atomic>
 
 #define RECYCLE_FREE_AST_INDICES
 
@@ -1518,7 +1519,7 @@ protected:
     app *                     m_true;
     app *                     m_false;
     proof *                   m_undef_proof;
-    unsigned                  m_fresh_id;
+    std::atomic<unsigned>     m_fresh_id;
     bool                      m_debug_ref_count;
     u_map<unsigned>           m_debug_free_indices;
     std::fstream*             m_trace_stream = nullptr;