diff --git a/lib/desugar.c b/lib/desugar.c
index b45749e..bbc7afd 100644
--- a/lib/desugar.c
+++ b/lib/desugar.c
@@ -5,8 +5,70 @@
 
 #include "desugar.h"
 
+#include <assert.h>
 #include <stdlib.h>
+#include <string.h>
+
+static void deep_copy_term(parse_term_t *dst, parse_term_t *src);
+
+static void deep_copy_sequence(parse_sequence_t *dst, parse_sequence_t *src)
+{
+	dst->count = dst->capacity = src->count;
+	dst->contents = malloc(dst->capacity * sizeof(parse_term_t));
+	for (int i = 0; i < dst->count; ++i)
+		deep_copy_term(&dst->contents[i], &src->contents[i]);
+}
+
+static void deep_copy_term(parse_term_t *dst, parse_term_t *src)
+{
+	assert(PARSE_TERM_WILDCARD != src->type);
+	assert(PARSE_TERM_CLASS != src->type);
+
+	memcpy(dst, src, sizeof(parse_term_t));
+	if (PARSE_TERM_SUBEXPR == src->type) {
+		dst->subexpr.capacity = src->subexpr.count;
+		dst->subexpr.contents
+		    = malloc(dst->subexpr.capacity * sizeof(parse_sequence_t));
+		for (int i = 0; i < dst->subexpr.count; ++i) {
+			deep_copy_sequence(
+			    &dst->subexpr.contents[i], &src->subexpr.contents[i]);
+		}
+	}
+}
+
+static void desugar_plus(parse_term_t *term)
+{
+	parse_sequence_t *alternatives = malloc(sizeof(parse_sequence_t));
+	alternatives[0].count = alternatives[0].capacity = 2;
+	alternatives[0].contents = malloc(2 * sizeof(parse_term_t));
+
+	memcpy(&alternatives[0].contents[0], term, sizeof(parse_term_t));
+	deep_copy_term(&alternatives[0].contents[1], term);
+	alternatives[0].contents[0].quantifier = PARSE_QUANTIFIER_NONE;
+	alternatives[0].contents[1].quantifier = PARSE_QUANTIFIER_STAR;
+
+	term->quantifier = PARSE_QUANTIFIER_NONE;
+	term->type = PARSE_TERM_SUBEXPR;
+	term->subexpr.count = term->subexpr.capacity = 1;
+	term->subexpr.contents = alternatives;
+}
+
+static void desugar_term(parse_term_t *term)
+{
+	switch (term->quantifier) {
+	case PARSE_QUANTIFIER_PLUS:
+		desugar_plus(term);
+		break;
+	case PARSE_QUANTIFIER_NONE:
+	case PARSE_QUANTIFIER_STAR:
+		break;
+	}
+}
 
 void desugar_regex(parse_tree_t *regex)
 {
+	for (int i = 0; i < regex->count; ++i) {
+		for (int j = 0; j < regex->contents[i].count; ++j)
+			desugar_term(&regex->contents[i].contents[j]);
+	}
 }
diff --git a/tests/desugar_tests.c b/tests/desugar_tests.c
index 6119fa9..d3902bf 100644
--- a/tests/desugar_tests.c
+++ b/tests/desugar_tests.c
@@ -140,6 +140,42 @@ static void subexpr_a_is_unchanged(void)
 	parse_free_tree_children(&t);
 }
 
+static void a_plus_becomes_subexpr_aa_star(void)
+{
+	parse_term_t *terms = malloc(1 * sizeof(parse_term_t));
+	terms[0].quantifier = PARSE_QUANTIFIER_PLUS;
+	terms[0].type = PARSE_TERM_LITERAL;
+	terms[0].literal = 'a';
+	parse_sequence_t *alternatives = malloc(1 * sizeof(parse_sequence_t));
+	alternatives[0].count = alternatives[0].capacity = 1;
+	alternatives[0].contents = terms;
+	parse_tree_t t = { .count = 1, .capacity = 1, .contents = alternatives };
+
+	desugar_regex(&t);
+	ASSERT_EQ(1, t.count);
+	ASSERT_NOT_NULL(t.contents);
+	ASSERT_EQ(1, t.contents[0].count);
+	ASSERT_NOT_NULL(t.contents[0].contents);
+	ASSERT_EQ(PARSE_QUANTIFIER_NONE, t.contents[0].contents[0].quantifier);
+	ASSERT_EQ(PARSE_TERM_SUBEXPR, t.contents[0].contents[0].type);
+
+	const parse_tree_t *inner = &t.contents[0].contents[0].subexpr;
+	ASSERT_EQ(1, inner->count);
+	ASSERT_NOT_NULL(inner->contents);
+	ASSERT_EQ(2, inner->contents[0].count);
+	ASSERT_NOT_NULL(inner->contents[0].contents);
+	ASSERT_EQ(
+	    PARSE_QUANTIFIER_NONE, inner->contents[0].contents[0].quantifier);
+	ASSERT_EQ(PARSE_TERM_LITERAL, inner->contents[0].contents[0].type);
+	ASSERT_EQ('a', inner->contents[0].contents[0].literal);
+	ASSERT_EQ(
+	    PARSE_QUANTIFIER_STAR, inner->contents[0].contents[1].quantifier);
+	ASSERT_EQ(PARSE_TERM_LITERAL, inner->contents[0].contents[1].type);
+	ASSERT_EQ('a', inner->contents[0].contents[1].literal);
+
+	parse_free_tree_children(&t);
+}
+
 int main(void)
 {
 	TESTING_BEGIN();
@@ -148,5 +184,6 @@ int main(void)
 	a_star_is_unchanged();
 	a_or_b_or_c_is_unchanged();
 	subexpr_a_is_unchanged();
+	a_plus_becomes_subexpr_aa_star();
 	return TESTING_END();
 }