diff --git a/src/apfl.h b/src/apfl.h
index 22722e2..74595f0 100644
--- a/src/apfl.h
+++ b/src/apfl.h
@@ -609,6 +609,8 @@ enum apfl_result apfl_push_bool(apfl_ctx, bool);
 enum apfl_result apfl_push_number(apfl_ctx, apfl_number);
 // Push a string onto the stack
 enum apfl_result apfl_push_string_view_copy(apfl_ctx, struct apfl_string_view);
+// Push a constant string.
+enum apfl_result apfl_push_const_string(apfl_ctx, const char *);
 // Create a new empty list on the stack
 enum apfl_result apfl_list_create(apfl_ctx, size_t initial_capacity);
 // Append a value to a list. The value will be dropped.
diff --git a/src/context.c b/src/context.c
index 1482bed..06d56a5 100644
--- a/src/context.c
+++ b/src/context.c
@@ -295,6 +295,15 @@ apfl_push_string_view_copy(apfl_ctx ctx, struct apfl_string_view sv)
     )
 }
 
+enum apfl_result
+apfl_push_const_string(apfl_ctx ctx, const char *string)
+{
+    return apfl_stack_push(ctx, (struct apfl_value) {
+        .type = VALUE_CONST_STRING,
+        .const_string = apfl_string_view_from(string),
+    }) ? APFL_RESULT_OK : APFL_RESULT_ERR_FATAL;
+}
+
 enum apfl_result
 apfl_list_create(apfl_ctx ctx, size_t initial_cap)
 {
diff --git a/src/value.c b/src/value.c
index 28334b4..2b67ff8 100644
--- a/src/value.c
+++ b/src/value.c
@@ -75,6 +75,19 @@ apfl_dict_deinit(struct dict_header *header)
     apfl_hashmap_deinit(&header->map);
 }
 
+static struct apfl_string_view
+as_string_view(struct apfl_value value)
+{
+    switch (value.type) {
+    case VALUE_STRING:
+        return apfl_string_view_from(*value.string);
+    case VALUE_CONST_STRING:
+        return value.const_string;
+    default:
+        return (struct apfl_string_view) { .bytes = NULL, .len = 0 };
+    }
+}
+
 static bool
 format(unsigned indent, struct apfl_format_writer w, struct apfl_value value, bool skip_first_indent)
 {
@@ -91,8 +104,9 @@ format(unsigned indent, struct apfl_format_writer w, struct apfl_value value, bo
         TRY(apfl_format_put_number(w, value.number));
         return true;
     case VALUE_STRING:
+    case VALUE_CONST_STRING:
         TRY(apfl_format_put_string(w, "\""));
-        TRY(apfl_format_put_string(w, *value.string));
+        TRY(apfl_format_put_string(w, as_string_view(value)));
         TRY(apfl_format_put_string(w, "\""));
         return true;
     case VALUE_LIST:
@@ -205,23 +219,21 @@ dict_eq(const apfl_dict a, const apfl_dict b)
 bool
 apfl_value_eq(const struct apfl_value a, const struct apfl_value b)
 {
-    if (a.type != b.type) {
-        return false;
-    }
-
     switch (a.type) {
     case VALUE_NIL:
-        return true;
+        return b.type == VALUE_NIL && true;
     case VALUE_BOOLEAN:
-        return a.boolean == b.boolean;
+        return b.type == VALUE_BOOLEAN && a.boolean == b.boolean;
     case VALUE_NUMBER:
-        return a.number == b.number;
+        return b.type == VALUE_NUMBER && a.number == b.number;
     case VALUE_STRING:
-        return a.string == b.string || apfl_string_eq(*a.string, *b.string);
+    case VALUE_CONST_STRING:
+        return (b.type == VALUE_STRING || b.type == VALUE_CONST_STRING)
+            && apfl_string_eq(as_string_view(a), as_string_view(b));
     case VALUE_LIST:
-        return list_eq(a.list, b.list);
+        return b.type == VALUE_LIST && list_eq(a.list, b.list);
     case VALUE_DICT:
-        return dict_eq(a.dict, b.dict);
+        return b.type == VALUE_DICT && dict_eq(a.dict, b.dict);
     }
 
     assert(false);
@@ -463,7 +475,8 @@ apfl_value_hash(const struct apfl_value value)
     case VALUE_NUMBER:
         return apfl_hash_fnv1a_add(&value.number, sizeof(apfl_number), hash);
     case VALUE_STRING:
-        sv = apfl_string_view_from(*value.string);
+    case VALUE_CONST_STRING:
+        sv = as_string_view(value);
         return apfl_hash_fnv1a_add(sv.bytes, sv.len, hash);
     case VALUE_LIST:
         for (size_t i = 0; i < value.list->len; i++) {
@@ -490,6 +503,7 @@ apfl_value_get_gc_object(struct apfl_value value)
     case VALUE_NIL:
     case VALUE_BOOLEAN:
     case VALUE_NUMBER:
+    case VALUE_CONST_STRING:
         return NULL;
     case VALUE_STRING:
         return GC_OBJECT_FROM(value.string, GC_TYPE_STRING);
diff --git a/src/value.h b/src/value.h
index 1effec0..789bc55 100644
--- a/src/value.h
+++ b/src/value.h
@@ -20,6 +20,7 @@ enum value_type {
     VALUE_BOOLEAN,
     VALUE_NUMBER,
     VALUE_STRING,
+    VALUE_CONST_STRING,
     VALUE_LIST,
     VALUE_DICT,
     // TODO: functions/closures
@@ -45,6 +46,7 @@ struct apfl_value {
         bool boolean;
         apfl_number number;
         struct apfl_string *string;
+        struct apfl_string_view const_string;
         struct list_header *list;
         struct dict_header *dict;
     };