diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 72fc2a349..b7ca95fa1 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -539,13 +539,6 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 }
 
 
-Ptr<Value> EvalState::allocValue()
-{
-    nrValues++;
-    return gc.alloc<Value>(Value::words());
-}
-
-
 Ptr<Env> EvalState::allocEnv(size_t size, size_t prevWith, Tag type)
 {
     nrEnvs++;
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 0ad6d6f24..c537dad53 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -286,7 +286,12 @@ public:
     void autoCallFunction(Bindings & args, Value & fun, Value & res);
 
     /* Allocation primitives. */
-    Ptr<Value> allocValue();
+    Ptr<Value> allocValue()
+    {
+        nrValues++;
+        return gc.alloc<Value>(Value::words());
+    }
+
     Ptr<Env> allocEnv(size_t size, size_t prevWith = 0, Tag type = tEnv);
 
     // Note: the resulting Value is only reachable as long as vAttrs