diff --git a/lib/isc/buffer.c b/lib/isc/buffer.c
index cecfecddd9..166d1ded4d 100644
--- a/lib/isc/buffer.c
+++ b/lib/isc/buffer.c
@@ -576,9 +576,6 @@ isc_buffer_reallocate(isc_buffer_t **dynbuffer, unsigned int length) {
 	REQUIRE(ISC_BUFFER_VALID(*dynbuffer));
 	REQUIRE((*dynbuffer)->mctx != NULL);
 
-	if ((*dynbuffer)->length > length)
-		return (ISC_R_NOSPACE);
-
 	/*
 	 * XXXMUKS: This is far more expensive than plain realloc() as
 	 * it doesn't remap pages, but does ordinary copy. So is
diff --git a/lib/isc/tests/buffer_test.c b/lib/isc/tests/buffer_test.c
index 70f49161c5..d584c51c23 100644
--- a/lib/isc/tests/buffer_test.c
+++ b/lib/isc/tests/buffer_test.c
@@ -114,12 +114,6 @@ ATF_TC_BODY(isc_buffer_reallocate, tc) {
 	ATF_REQUIRE(b != NULL);
 	ATF_CHECK_EQ(b->length, 1024);
 
-	result = isc_buffer_reallocate(&b, 512);
-	ATF_CHECK_EQ(result, ISC_R_NOSPACE);
-	ATF_CHECK(ISC_BUFFER_VALID(b));
-	ATF_REQUIRE(b != NULL);
-	ATF_CHECK_EQ(b->length, 1024);
-
 	result = isc_buffer_reallocate(&b, 1536);
 	ATF_CHECK_EQ(result, ISC_R_SUCCESS);
 	ATF_CHECK(ISC_BUFFER_VALID(b));