diff --git a/contrib/btree_gist/btree_numeric.c b/contrib/btree_gist/btree_numeric.c
index 373d12e..f8c0f60 100644
--- a/contrib/btree_gist/btree_numeric.c
+++ b/contrib/btree_gist/btree_numeric.c
@@ -185,9 +185,9 @@ gbt_numeric_penalty(PG_FUNCTION_ARGS)
 											 NumericGetDatum(os)
 											 ));
 
-	if (NUMERIC_IS_NAN(us))
+	if (numeric_is_nan(us))
 	{
-		if (NUMERIC_IS_NAN(os))
+		if (numeric_is_nan(os))
 			*result = 0.0;
 		else
 			*result = 1.0;
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 5766a8b..6f18639 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -35,6 +35,37 @@
 #include "utils/int8.h"
 #include "utils/numeric.h"
 
+/*
+ * Sign values and macros to deal with packing/unpacking n_sign_dscale
+ */
+#define NUMERIC_SIGN_MASK	0xC000
+#define NUMERIC_POS			0x0000
+#define NUMERIC_NEG			0x4000
+#define NUMERIC_NAN			0xC000
+#define NUMERIC_DSCALE_MASK 0x3FFF
+#define NUMERIC_SIGN(n)		((n)->n_sign_dscale & NUMERIC_SIGN_MASK)
+#define NUMERIC_DSCALE(n)	((n)->n_sign_dscale & NUMERIC_DSCALE_MASK)
+#define NUMERIC_IS_NAN(n)	(NUMERIC_SIGN(n) != NUMERIC_POS &&	\
+							 NUMERIC_SIGN(n) != NUMERIC_NEG)
+
+
+/*
+ * The Numeric data type stored in the database
+ *
+ * NOTE: by convention, values in the packed form have been stripped of
+ * all leading and trailing zero digits (where a "digit" is of base NBASE).
+ * In particular, if the value is zero, there will be no digits at all!
+ * The weight is arbitrary in that case, but we normally set it to zero.
+ */
+struct NumericData
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	uint16		n_sign_dscale;	/* Sign + display scale */
+	int16		n_weight;		/* Weight of 1st digit	*/
+	char		n_data[1];		/* Digits (really array of NumericDigit) */
+};
+
+
 /* ----------
  * Uncomment the following to enable compilation of dump_numeric()
  * and dump_var() and to get a dump of any result produced by make_result().
@@ -428,6 +459,17 @@ numeric_out(PG_FUNCTION_ARGS)
 }
 
 /*
+ * numeric_is_nan() -
+ *
+ *  Is Numeric value a NaN?
+ */
+bool
+numeric_is_nan(Numeric num)
+{
+	return NUMERIC_IS_NAN(num);
+}
+
+/*
  * numeric_out_sci() -
  *
  *	Output function for numeric data type in scientific notation.
diff --git a/src/include/utils/numeric.h b/src/include/utils/numeric.h
index 73c1ee1..0145f0c 100644
--- a/src/include/utils/numeric.h
+++ b/src/include/utils/numeric.h
@@ -37,41 +37,10 @@
  */
 #define NUMERIC_MIN_SIG_DIGITS		16
 
-
-/*
- * Sign values and macros to deal with packing/unpacking n_sign_dscale
- */
-#define NUMERIC_SIGN_MASK	0xC000
-#define NUMERIC_POS			0x0000
-#define NUMERIC_NEG			0x4000
-#define NUMERIC_NAN			0xC000
-#define NUMERIC_DSCALE_MASK 0x3FFF
-#define NUMERIC_SIGN(n)		((n)->n_sign_dscale & NUMERIC_SIGN_MASK)
-#define NUMERIC_DSCALE(n)	((n)->n_sign_dscale & NUMERIC_DSCALE_MASK)
-#define NUMERIC_IS_NAN(n)	(NUMERIC_SIGN(n) != NUMERIC_POS &&	\
-							 NUMERIC_SIGN(n) != NUMERIC_NEG)
-
-
-/*
- * The Numeric data type stored in the database
- *
- * NOTE: by convention, values in the packed form have been stripped of
- * all leading and trailing zero digits (where a "digit" is of base NBASE).
- * In particular, if the value is zero, there will be no digits at all!
- * The weight is arbitrary in that case, but we normally set it to zero.
- */
-typedef struct NumericData
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	uint16		n_sign_dscale;	/* Sign + display scale */
-	int16		n_weight;		/* Weight of 1st digit	*/
-	char		n_data[1];		/* Digits (really array of NumericDigit) */
-} NumericData;
-
-typedef NumericData *Numeric;
-
 #define NUMERIC_HDRSZ	(VARHDRSZ + sizeof(uint16) + sizeof(int16))
 
+struct NumericData;
+typedef struct NumericData *Numeric;
 
 /*
  * fmgr interface macros
@@ -87,6 +56,7 @@ typedef NumericData *Numeric;
 /*
  * Utility functions in numeric.c
  */
+extern bool numeric_is_nan(Numeric num);
 extern char *numeric_out_sci(Numeric num, int scale);
 
 #endif   /* _PG_NUMERIC_H_ */