diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index 3331a7643..08a419923 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -42,6 +42,7 @@ inline void * allocBytes(size_t n)
 [[gnu::always_inline]]
 Value * EvalState::allocValue()
 {
+#if HAVE_BOEHMGC
     /* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
        GC_malloc_many returns a linked list of objects of the given size, where the first word
        of each object is also the pointer to the next object in the list. This also means that we
@@ -56,6 +57,9 @@ Value * EvalState::allocValue()
     void * p = *valueAllocCache;
     *valueAllocCache = GC_NEXT(p);
     GC_NEXT(p) = nullptr;
+#else
+    void * p = allocBytes(sizeof(Value));
+#endif
 
     nrValues++;
     return (Value *) p;
@@ -70,9 +74,8 @@ Env & EvalState::allocEnv(size_t size)
 
     Env * env;
 
-    if (size != 1)
-        env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
-    else {
+#if HAVE_BOEHMGC
+    if (size == 1) {
         /* see allocValue for explanations. */
         if (!*env1AllocCache) {
             *env1AllocCache = GC_malloc_many(sizeof(Env) + sizeof(Value *));
@@ -83,7 +86,9 @@ Env & EvalState::allocEnv(size_t size)
         *env1AllocCache = GC_NEXT(p);
         GC_NEXT(p) = nullptr;
         env = (Env *) p;
-    }
+    } else
+#endif
+        env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
 
     env->type = Env::Plain;
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index d2efe8a47..f1e00bae7 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -133,11 +133,13 @@ private:
     /* Cache used by prim_match(). */
     std::shared_ptr<RegexCache> regexCache;
 
+#if HAVE_BOEHMGC
     /* Allocation cache for GC'd Value objects. */
     std::shared_ptr<void *> valueAllocCache;
 
     /* Allocation cache for size-1 Env objects. */
     std::shared_ptr<void *> env1AllocCache;
+#endif
 
 public: