diff --git a/t/core_partial_read.t b/t/core_partial_read.t
index 697c788..762135e 100644
--- a/t/core_partial_read.t
+++ b/t/core_partial_read.t
@@ -9,6 +9,7 @@ use English qw( -no_match_vars );
 use Exporter();
 use XSLoader();
 use constant;
+use overload;
 
 SKIP: {
 	if ($^O eq 'MSWin32') {
diff --git a/t/core_read.t b/t/core_read.t
index 3ab5174..7a73b81 100644
--- a/t/core_read.t
+++ b/t/core_read.t
@@ -9,6 +9,7 @@ use English qw( -no_match_vars );
 use Exporter();
 use XSLoader();
 use constant;
+use overload;
 BEGIN {
 	if ($^O eq 'MSWin32') {
 		require Win32;
diff --git a/t/core_sysopen.t b/t/core_sysopen.t
index 468c489..0804ce0 100644
--- a/t/core_sysopen.t
+++ b/t/core_sysopen.t
@@ -9,6 +9,7 @@ use English qw( -no_match_vars );
 use Exporter();
 use XSLoader();
 use constant;
+use overload;
 
 SKIP: {
 	if ($^O eq 'MSWin32') {
diff --git a/t/pp.t b/t/pp.t
index fc323f3..a42858e 100644
--- a/t/pp.t
+++ b/t/pp.t
@@ -6,6 +6,7 @@ use English qw( -no_match_vars );
 use Exporter();
 use XSLoader();
 use constant;
+use overload;
 BEGIN {
 	if ($^O eq 'MSWin32') {
 		require Win32;