diff --git a/src/vector.c b/src/vector.c
index 3b4d0f2..7aa75d0 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -5,7 +5,6 @@
 #include "vector.h"
 #include "fmgr.h"
 #include "catalog/pg_type.h"
-#include "common/shortest_dec.h"
 #include "lib/stringinfo.h"
 #include "libpq/pqformat.h"
 #include "utils/array.h"
@@ -14,7 +13,10 @@
 #include "utils/numeric.h"
 
 #if PG_VERSION_NUM >= 120000
+#include "common/shortest_dec.h"
 #include "utils/float.h"
+#else
+#include <float.h>
 #endif
 
 #if PG_VERSION_NUM < 130000
@@ -195,6 +197,15 @@ vector_out(PG_FUNCTION_ARGS)
 	int			i;
 	int			n;
 
+#if PG_VERSION_NUM < 120000
+	int			ndig = FLT_DIG + extra_float_digits;
+
+	if (ndig < 1)
+		ndig = 1;
+
+#define FLOAT_SHORTEST_DECIMAL_LEN ndig + 10
+#endif
+
 	/*
 	 * Need:
 	 *
@@ -218,7 +229,11 @@ vector_out(PG_FUNCTION_ARGS)
 			ptr++;
 		}
 
+#if PG_VERSION_NUM >= 120000
 		n = float_to_shortest_decimal_bufn(vector->x[i], ptr);
+#else
+		n = sprintf(ptr, "%.*g", ndig, vector->x[i]);
+#endif
 		ptr += n;
 	}
 	*ptr = ']';