diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 9b33fb8d722..3248fb51080 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -407,7 +407,7 @@ octfail			0[oO]_?
 binfail			0[bB]_?
 
 numeric			(({decinteger}\.{decinteger}?)|(\.{decinteger}))
-numericfail		{decdigit}+\.\.
+numericfail		{decinteger}\.\.
 
 real			({decinteger}|{numeric})[Ee][-+]?{decinteger}
 realfail		({decinteger}|{numeric})[Ee][-+]
diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
index c6d02439ab2..ddc4658b925 100644
--- a/src/fe_utils/psqlscan.l
+++ b/src/fe_utils/psqlscan.l
@@ -343,7 +343,7 @@ octfail			0[oO]_?
 binfail			0[bB]_?
 
 numeric			(({decinteger}\.{decinteger}?)|(\.{decinteger}))
-numericfail		{decdigit}+\.\.
+numericfail		{decinteger}\.\.
 
 real			({decinteger}|{numeric})[Ee][-+]?{decinteger}
 realfail		({decinteger}|{numeric})[Ee][-+]
diff --git a/src/interfaces/ecpg/preproc/pgc.l b/src/interfaces/ecpg/preproc/pgc.l
index d117cafce65..f9d68a96e79 100644
--- a/src/interfaces/ecpg/preproc/pgc.l
+++ b/src/interfaces/ecpg/preproc/pgc.l
@@ -376,7 +376,7 @@ octfail			0[oO]_?
 binfail			0[bB]_?
 
 numeric			(({decinteger}\.{decinteger}?)|(\.{decinteger}))
-numericfail		{decdigit}+\.\.
+numericfail		{decinteger}\.\.
 
 real			({decinteger}|{numeric})[Ee][-+]?{decinteger}
 realfail		({decinteger}|{numeric})[Ee][-+]
diff --git a/src/test/regress/expected/numerology.out b/src/test/regress/expected/numerology.out
index c8196d2c85a..8d4a3ba228a 100644
--- a/src/test/regress/expected/numerology.out
+++ b/src/test/regress/expected/numerology.out
@@ -297,6 +297,17 @@ SELECT 1_000.5e0_1;
     10005
 (1 row)
 
+DO $$
+DECLARE
+  i int;
+BEGIN
+  FOR i IN 1_001..1_003 LOOP
+    RAISE NOTICE 'i = %', i;
+  END LOOP;
+END $$;
+NOTICE:  i = 1001
+NOTICE:  i = 1002
+NOTICE:  i = 1003
 -- error cases
 SELECT _100;
 ERROR:  column "_100" does not exist
diff --git a/src/test/regress/sql/numerology.sql b/src/test/regress/sql/numerology.sql
index 3f0ec34ecfa..372e7bf9bc8 100644
--- a/src/test/regress/sql/numerology.sql
+++ b/src/test/regress/sql/numerology.sql
@@ -77,6 +77,15 @@ SELECT 1_000.;
 SELECT .000_005;
 SELECT 1_000.5e0_1;
 
+DO $$
+DECLARE
+  i int;
+BEGIN
+  FOR i IN 1_001..1_003 LOOP
+    RAISE NOTICE 'i = %', i;
+  END LOOP;
+END $$;
+
 -- error cases
 SELECT _100;
 SELECT 100_;