diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1c4f9ac04e6..fe6c6f8a05a 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -6240,15 +6240,13 @@ parse_real(const char *value, double *result, int flags, const char **hintmsg)
 	if (hintmsg)
 		*hintmsg = NULL;
 
+	errno = 0;
 	val = strtod(value, &endptr);
-	if (endptr == value)
-		return false;			/* no HINT for syntax error */
 
-	/*
-	 * We ignore strtod's errno, so that out-of-range inputs will just result
-	 * in zero or infinity values.  Subsequent range checks will reject those
-	 * if necessary.  We do need to reject NaN explicitly, however.
-	 */
+	if (endptr == value || errno == ERANGE)
+		return false;			/* no HINT for these cases */
+
+	/* reject NaN (infinities will fail range checks later) */
 	if (isnan(val))
 		return false;			/* treat same as syntax error; no HINT */
 
diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out
index f2590ee6769..811f80a0976 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -511,8 +511,6 @@ SET seq_page_cost TO 'NaN';
 ERROR:  invalid value for parameter "seq_page_cost": "NaN"
 SET vacuum_cost_delay TO '10s';
 ERROR:  10000 ms is outside the valid range for parameter "vacuum_cost_delay" (0 .. 100)
-SET geqo_selection_bias TO '-infinity';
-ERROR:  -Infinity is outside the valid range for parameter "geqo_selection_bias" (1.5 .. 2)
 --
 -- Test DISCARD TEMP
 --
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index b3ca59c09b1..43dbba3775e 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -147,7 +147,6 @@ SELECT '2006-08-13 12:34:56'::timestamptz;
 -- Test some simple error cases
 SET seq_page_cost TO 'NaN';
 SET vacuum_cost_delay TO '10s';
-SET geqo_selection_bias TO '-infinity';
 
 --
 -- Test DISCARD TEMP