diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 3e5614ece30..7dc0df52634 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -3073,7 +3073,12 @@ float8_numeric(PG_FUNCTION_ARGS)
 	if (isnan(val))
 		PG_RETURN_NUMERIC(make_result(&const_nan));
 
-	sprintf(buf, "%.*g", DBL_DIG, val);
+	if (isinf(val))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot convert infinity to numeric")));
+
+	snprintf(buf, sizeof(buf), "%.*g", DBL_DIG, val);
 
 	init_var(&result);
 
@@ -3139,7 +3144,12 @@ float4_numeric(PG_FUNCTION_ARGS)
 	if (isnan(val))
 		PG_RETURN_NUMERIC(make_result(&const_nan));
 
-	sprintf(buf, "%.*g", FLT_DIG, val);
+	if (isinf(val))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot convert infinity to numeric")));
+
+	snprintf(buf, sizeof(buf), "%.*g", FLT_DIG, val);
 
 	init_var(&result);
 
diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index ae0beb9b68f..7e55b0e2931 100644
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -708,6 +708,27 @@ SELECT * FROM fract_only;
 (6 rows)
 
 DROP TABLE fract_only;
+-- Check inf/nan conversion behavior
+SELECT 'NaN'::float8::numeric;
+ numeric 
+---------
+     NaN
+(1 row)
+
+SELECT 'Infinity'::float8::numeric;
+ERROR:  cannot convert infinity to numeric
+SELECT '-Infinity'::float8::numeric;
+ERROR:  cannot convert infinity to numeric
+SELECT 'NaN'::float4::numeric;
+ numeric 
+---------
+     NaN
+(1 row)
+
+SELECT 'Infinity'::float4::numeric;
+ERROR:  cannot convert infinity to numeric
+SELECT '-Infinity'::float4::numeric;
+ERROR:  cannot convert infinity to numeric
 -- Simple check that ceil(), floor(), and round() work correctly
 CREATE TABLE ceil_floor_round (a numeric);
 INSERT INTO ceil_floor_round VALUES ('-5.5');
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index b51225c47f3..9675b6eabf3 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -655,6 +655,14 @@ INSERT INTO fract_only VALUES (8, '0.00017');
 SELECT * FROM fract_only;
 DROP TABLE fract_only;
 
+-- Check inf/nan conversion behavior
+SELECT 'NaN'::float8::numeric;
+SELECT 'Infinity'::float8::numeric;
+SELECT '-Infinity'::float8::numeric;
+SELECT 'NaN'::float4::numeric;
+SELECT 'Infinity'::float4::numeric;
+SELECT '-Infinity'::float4::numeric;
+
 -- Simple check that ceil(), floor(), and round() work correctly
 CREATE TABLE ceil_floor_round (a numeric);
 INSERT INTO ceil_floor_round VALUES ('-5.5');