diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 55f8abcb7..7a8e93c12 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -405,7 +405,7 @@ expr_select
 expr_simple
   : ID {
       std::string_view s = "__curPos";
-      if (strncmp($1.p, s.data(), s.size()) == 0)
+      if ($1.l == s.size() && strncmp($1.p, s.data(), s.size()) == 0)
           $$ = new ExprPos(CUR_POS);
       else
           $$ = new ExprVar(CUR_POS, data->symbols.create($1));
diff --git a/tests/lang/eval-okay-regression-20220125.exp b/tests/lang/eval-okay-regression-20220125.exp
new file mode 100644
index 000000000..00750edc0
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220125.exp
@@ -0,0 +1 @@
+3
diff --git a/tests/lang/eval-okay-regression-20220125.nix b/tests/lang/eval-okay-regression-20220125.nix
new file mode 100644
index 000000000..485502373
--- /dev/null
+++ b/tests/lang/eval-okay-regression-20220125.nix
@@ -0,0 +1,2 @@
+((__curPosFoo: __curPosFoo) 1) + ((__curPosBar: __curPosBar) 2)
+