diff --git a/tests/micropython/import_mpy_invalid.py b/tests/micropython/import_mpy_invalid.py
index d6d01e7f1f..00973fe3f9 100644
--- a/tests/micropython/import_mpy_invalid.py
+++ b/tests/micropython/import_mpy_invalid.py
@@ -1,11 +1,9 @@
 # test importing of invalid .mpy files
 
-import sys, uio
-
 try:
-    uio.IOBase
-    import uos
+    import sys, uio, uos
 
+    uio.IOBase
     uos.mount
 except (ImportError, AttributeError):
     print("SKIP")
@@ -14,18 +12,13 @@ except (ImportError, AttributeError):
 
 class UserFile(uio.IOBase):
     def __init__(self, data):
-        self.data = data
+        self.data = memoryview(data)
         self.pos = 0
 
-    def read(self):
-        return self.data
-
     def readinto(self, buf):
-        n = 0
-        while n < len(buf) and self.pos < len(self.data):
-            buf[n] = self.data[self.pos]
-            n += 1
-            self.pos += 1
+        n = min(len(buf), len(self.data) - self.pos)
+        buf[:n] = self.data[self.pos : self.pos + n]
+        self.pos += n
         return n
 
     def ioctl(self, req, arg):
diff --git a/tests/micropython/import_mpy_native_x64.py b/tests/micropython/import_mpy_native_x64.py
index 5d7bdab4a2..d0de507d44 100644
--- a/tests/micropython/import_mpy_native_x64.py
+++ b/tests/micropython/import_mpy_native_x64.py
@@ -1,11 +1,9 @@
 # test importing of .mpy files with native code (x64 only)
 
-import sys, uio
-
 try:
-    uio.IOBase
-    import uos
+    import sys, uio, uos
 
+    uio.IOBase
     uos.mount
 except (ImportError, AttributeError):
     print("SKIP")
@@ -18,18 +16,13 @@ if not (sys.platform == "linux" and sys.maxsize > 2 ** 32):
 
 class UserFile(uio.IOBase):
     def __init__(self, data):
-        self.data = data
+        self.data = memoryview(data)
         self.pos = 0
 
-    def read(self):
-        return self.data
-
     def readinto(self, buf):
-        n = 0
-        while n < len(buf) and self.pos < len(self.data):
-            buf[n] = self.data[self.pos]
-            n += 1
-            self.pos += 1
+        n = min(len(buf), len(self.data) - self.pos)
+        buf[:n] = self.data[self.pos : self.pos + n]
+        self.pos += n
         return n
 
     def ioctl(self, req, arg):