diff --git a/src/halfvec.c b/src/halfvec.c
index 6195fbe..9e937b0 100644
--- a/src/halfvec.c
+++ b/src/halfvec.c
@@ -741,6 +741,27 @@ halfvec_to_vector(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(result);
 }
 
+/*
+ * Convert vector to half vec
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_to_halfvec);
+Datum
+vector_to_halfvec(PG_FUNCTION_ARGS)
+{
+	Vector	   *vec = PG_GETARG_VECTOR_P(0);
+
+	/* TODO Check halfvec dims in InitHalfVector */
+	HalfVector *result = InitHalfVector(vec->dim);
+
+	for (int i = 0; i < vec->dim; i++)
+	{
+		result->x[i] = Float4ToHalfUnchecked(vec->x[i]);
+		CheckElement(result->x[i]);
+	}
+
+	PG_RETURN_POINTER(result);
+}
+
 /*
  * Get the L2 distance between half vectors
  */
diff --git a/src/vector.c b/src/vector.c
index d082262..2d0e96a 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -533,24 +533,6 @@ vector_to_float4(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(result);
 }
 
-/*
- * Convert vector to half vec
- */
-PGDLLEXPORT PG_FUNCTION_INFO_V1(vector_to_halfvec);
-Datum
-vector_to_halfvec(PG_FUNCTION_ARGS)
-{
-	Vector	   *vec = PG_GETARG_VECTOR_P(0);
-
-	/* TODO Check halfvec dims in InitHalfVector */
-	HalfVector *result = InitHalfVector(vec->dim);
-
-	for (int i = 0; i < vec->dim; i++)
-		result->x[i] = Float4ToHalf(vec->x[i]);
-
-	PG_RETURN_POINTER(result);
-}
-
 /*
  * Get the L2 distance between vectors
  */
diff --git a/test/expected/cast.out b/test/expected/cast.out
index d438052..f2e1ce7 100644
--- a/test/expected/cast.out
+++ b/test/expected/cast.out
@@ -58,6 +58,12 @@ SELECT '[1,2,3]'::halfvec::vector;
  [1,2,3]
 (1 row)
 
+SELECT '[1e-8]'::vector::halfvec;
+ halfvec 
+---------
+ [0]
+(1 row)
+
 SELECT array_agg(n)::vector FROM generate_series(1, 16001) n;
 ERROR:  vector cannot have more than 16000 dimensions
 SELECT array_to_vector(array_agg(n), 16001, false) FROM generate_series(1, 16001) n;
diff --git a/test/sql/cast.sql b/test/sql/cast.sql
index fb574be..b86f4be 100644
--- a/test/sql/cast.sql
+++ b/test/sql/cast.sql
@@ -12,6 +12,7 @@ SELECT '{{1}}'::real[]::vector;
 SELECT '[1,2,3]'::vector::real[];
 SELECT '[1,2,3]'::vector::halfvec;
 SELECT '[1,2,3]'::halfvec::vector;
+SELECT '[1e-8]'::vector::halfvec;
 SELECT array_agg(n)::vector FROM generate_series(1, 16001) n;
 SELECT array_to_vector(array_agg(n), 16001, false) FROM generate_series(1, 16001) n;