diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
index 81d724e499e..0326544d47b 100644
--- a/src/backend/utils/adt/float.c
+++ b/src/backend/utils/adt/float.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.130.2.1 2007/09/19 22:31:51 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.130.2.2 2009/03/04 22:08:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,6 +110,15 @@ static int	float4_cmp_internal(float4 a, float4 b);
 static int	float8_cmp_internal(float8 a, float8 b);
 
 #ifndef HAVE_CBRT
+/*
+ * Some machines (in particular, some versions of AIX) have an extern
+ * declaration for cbrt() in <math.h> but fail to provide the actual
+ * function, which causes configure to not set HAVE_CBRT.  Furthermore,
+ * their compilers spit up at the mismatch between extern declaration
+ * and static definition.  We work around that here by the expedient
+ * of a #define to make the actual name of the static function different.
+ */
+#define cbrt my_cbrt
 static double cbrt(double x);
 #endif   /* HAVE_CBRT */