--- a/libvbisam/isdecimal.c
+++ b/libvbisam/isdecimal.c
@@ -134,6 +134,9 @@
 	int		decpt;
 	int		sign;
 
+#ifdef __ANDROID__
+	char *ecvt(double, int, int *, int *);
+#endif
 	str = (unsigned char *)ecvt (dbl, ndigits, &decpt, &sign);
 
 	dp->dec_pos = sign ? 0 : 1;
