diff --git a/src/xkbcomp/expr.c b/src/xkbcomp/expr.c
index c8197d1..a66729b 100644
--- a/src/xkbcomp/expr.c
+++ b/src/xkbcomp/expr.c
@@ -81,7 +81,7 @@ SimpleLookup(struct xkb_context *ctx, const void *priv, xkb_atom_t field,
     return false;
 }
 
-bool
+static bool
 LookupModIndex(struct xkb_context *ctx, const void *priv, xkb_atom_t field,
                enum expr_value_type type, xkb_mod_index_t *val_rtrn)
 {
diff --git a/src/xkbcomp/expr.h b/src/xkbcomp/expr.h
index a5abce1..14a6179 100644
--- a/src/xkbcomp/expr.h
+++ b/src/xkbcomp/expr.h
@@ -32,10 +32,6 @@ ExprResolveLhs(struct xkb_context *ctx, const ExprDef *expr,
                const char **elem_rtrn, const char **field_rtrn,
                ExprDef **index_rtrn);
 
-bool
-LookupModIndex(struct xkb_context *ctx, const void *priv, xkb_atom_t field,
-               enum expr_value_type type, xkb_mod_index_t *val_rtrn);
-
 bool
 ExprResolveModMask(struct xkb_context *ctx, const ExprDef *expr,
                    xkb_mod_mask_t *mask_rtrn);
diff --git a/src/xkbcomp/symbols.c b/src/xkbcomp/symbols.c
index 06661ae..592e991 100644
--- a/src/xkbcomp/symbols.c
+++ b/src/xkbcomp/symbols.c
@@ -1209,7 +1209,8 @@ HandleModMapDef(SymbolsInfo *info, ModMapDef *def)
     bool ok;
     struct xkb_context *ctx = info->keymap->ctx;
 
-    if (!LookupModIndex(ctx, NULL, def->modifier, EXPR_TYPE_INT, &ndx)) {
+    ndx = ModNameToIndex(xkb_atom_text(ctx, def->modifier));
+    if (ndx == XKB_MOD_INVALID) {
         log_err(info->keymap->ctx,
                 "Illegal modifier map definition; "
                 "Ignoring map for non-modifier \"%s\"\n",