diff --git a/include/xo/parser/parser.hpp b/include/xo/parser/parser.hpp
index 6b474ff5..39d768d8 100644
--- a/include/xo/parser/parser.hpp
+++ b/include/xo/parser/parser.hpp
@@ -244,7 +244,7 @@ namespace xo {
             expraction on_def(exprstatestack * p_stack);
             expraction on_symbol(const token_type & tk, exprstatestack * p_stack);
             expraction on_colon(exprstatestack * p_stack);
-            expraction on_singleassign();
+            expraction on_singleassign(exprstatestack * p_stack);
             expraction on_f64(const token_type & tk);
 
         private:
diff --git a/src/parser/parser.cpp b/src/parser/parser.cpp
index 0b1436cd..7302bd3b 100644
--- a/src/parser/parser.cpp
+++ b/src/parser/parser.cpp
@@ -415,7 +415,7 @@ namespace xo {
         }
 
         expraction
-        exprstate::on_singleassign() {
+        exprstate::on_singleassign(exprstatestack * /*p_stack*/) {
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
@@ -516,7 +516,7 @@ namespace xo {
                 return expraction();
 
             case tokentype::tk_singleassign:
-                return this->on_singleassign();
+                return this->on_singleassign(p_stack);
 
             case tokentype::tk_assign:
             case tokentype::tk_yields: