diff --git a/CHANGES.rst b/CHANGES.rst
index 360f828ab0..d2b2e0b879 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -8,7 +8,7 @@ Changes to be released in next version
  * 
 
 🐛 Bugfix
- * 
+ * Remove padding from base64 encoded `iv` value (vector-im/element-ios/issues/4172).
 
 ⚠️ API Changes
  * 
diff --git a/MatrixSDK/Crypto/Data/MXEncryptedAttachments.m b/MatrixSDK/Crypto/Data/MXEncryptedAttachments.m
index 3c74aae337..c7c0fe658f 100644
--- a/MatrixSDK/Crypto/Data/MXEncryptedAttachments.m
+++ b/MatrixSDK/Crypto/Data/MXEncryptedAttachments.m
@@ -170,7 +170,7 @@ + (void)encryptAttachment:(MXMediaLoader *)uploader
         encryptedContentFile.url = url;
         encryptedContentFile.mimetype = mimeType;
         encryptedContentFile.key = encryptedContentKey;
-        encryptedContentFile.iv = [iv base64EncodedStringWithOptions:0];
+        encryptedContentFile.iv = [MXBase64Tools base64ToUnpaddedBase64:[iv base64EncodedStringWithOptions:0]];
         encryptedContentFile.hashes = @{
                                         @"sha256": [MXBase64Tools base64ToUnpaddedBase64:[computedSha256 base64EncodedStringWithOptions:0]],
                                         };