diff --git a/src/common/unicode_norm.c b/src/common/unicode_norm.c
index 36ff2aab21..06bf921e45 100644
--- a/src/common/unicode_norm.c
+++ b/src/common/unicode_norm.c
@@ -439,6 +439,10 @@ unicode_normalize(UnicodeNormalizationForm form, const pg_wchar *input)
 	decomp_chars[decomp_size] = '\0';
 	Assert(decomp_size == current_size);
 
+	/* Leave if there is nothing to decompose */
+	if (decomp_size == 0)
+		return decomp_chars;
+
 	/*
 	 * Now apply canonical ordering.
 	 */
diff --git a/src/test/regress/expected/unicode.out b/src/test/regress/expected/unicode.out
index 2a1e903696..f2713a2326 100644
--- a/src/test/regress/expected/unicode.out
+++ b/src/test/regress/expected/unicode.out
@@ -8,6 +8,12 @@ SELECT U&'\0061\0308bc' <> U&'\00E4bc' COLLATE "C" AS sanity_check;
  t
 (1 row)
 
+SELECT normalize('');
+ normalize 
+-----------
+ 
+(1 row)
+
 SELECT normalize(U&'\0061\0308\24D1c') = U&'\00E4\24D1c' COLLATE "C" AS test_default;
  test_default 
 --------------
@@ -67,7 +73,8 @@ FROM
   (VALUES (1, U&'\00E4bc'),
           (2, U&'\0061\0308bc'),
           (3, U&'\00E4\24D1c'),
-          (4, U&'\0061\0308\24D1c')) vals (num, val)
+          (4, U&'\0061\0308\24D1c'),
+          (5, '')) vals (num, val)
 ORDER BY num;
  num | val | nfc | nfd | nfkc | nfkd 
 -----+-----+-----+-----+------+------
@@ -75,7 +82,8 @@ ORDER BY num;
    2 | äbc | f   | t   | f    | t
    3 | äⓑc | t   | f   | f    | f
    4 | äⓑc | f   | t   | f    | f
-(4 rows)
+   5 |     | t   | t   | t    | t
+(5 rows)
 
 SELECT is_normalized('abc', 'def');  -- run-time error
 ERROR:  invalid normalization form: def
diff --git a/src/test/regress/sql/unicode.sql b/src/test/regress/sql/unicode.sql
index ccfc6fa77a..63cd523f85 100644
--- a/src/test/regress/sql/unicode.sql
+++ b/src/test/regress/sql/unicode.sql
@@ -5,6 +5,7 @@ SELECT getdatabaseencoding() <> 'UTF8' AS skip_test \gset
 
 SELECT U&'\0061\0308bc' <> U&'\00E4bc' COLLATE "C" AS sanity_check;
 
+SELECT normalize('');
 SELECT normalize(U&'\0061\0308\24D1c') = U&'\00E4\24D1c' COLLATE "C" AS test_default;
 SELECT normalize(U&'\0061\0308\24D1c', NFC) = U&'\00E4\24D1c' COLLATE "C" AS test_nfc;
 SELECT normalize(U&'\00E4bc', NFC) = U&'\00E4bc' COLLATE "C" AS test_nfc_idem;
@@ -26,7 +27,8 @@ FROM
   (VALUES (1, U&'\00E4bc'),
           (2, U&'\0061\0308bc'),
           (3, U&'\00E4\24D1c'),
-          (4, U&'\0061\0308\24D1c')) vals (num, val)
+          (4, U&'\0061\0308\24D1c'),
+          (5, '')) vals (num, val)
 ORDER BY num;
 
 SELECT is_normalized('abc', 'def');  -- run-time error