diff --git a/src/sparsevec.c b/src/sparsevec.c
index 0511e4f..1a82d7d 100644
--- a/src/sparsevec.c
+++ b/src/sparsevec.c
@@ -570,7 +570,7 @@ vector_to_sparsevec(PG_FUNCTION_ARGS)
 			if (j == nnz)
 				elog(ERROR, "safety check failed");
 
-			result->indices[j] = i;
+			result->indices[j] = i + 1;
 			values[j] = vec->x[i];
 			j++;
 		}
diff --git a/test/expected/sparsevec_input.out b/test/expected/sparsevec_input.out
index c25b852..6fb400a 100644
--- a/test/expected/sparsevec_input.out
+++ b/test/expected/sparsevec_input.out
@@ -21,7 +21,7 @@ ERROR:  expected 4 dimensions, not 5
 SELECT '[0,1.5,0,3.5,0]'::vector::sparsevec;
     sparsevec    
 -----------------
- {1:1.5,3:3.5}/5
+ {2:1.5,4:3.5}/5
 (1 row)
 
 SELECT '{1:0,2:1,3:0}/3'::sparsevec;