diff --git a/xcode/OLMKit/OLMAccount.m b/xcode/OLMKit/OLMAccount.m
index 058b389..9e48c2d 100644
--- a/xcode/OLMKit/OLMAccount.m
+++ b/xcode/OLMKit/OLMAccount.m
@@ -193,6 +193,7 @@
     }
     NSMutableData *pickle = [serializedData dataUsingEncoding:NSUTF8StringEncoding].mutableCopy;
     size_t result = olm_unpickle_account(_account, key.bytes, key.length, pickle.mutableBytes, pickle.length);
+    [pickle resetBytesInRange:NSMakeRange(0, pickle.length)];
     if (result == olm_error()) {
         const char *olm_error = olm_account_last_error(_account);
         NSString *errorString = [NSString stringWithUTF8String:olm_error];
@@ -219,6 +220,7 @@
         return nil;
     }
     NSString *pickleString = [[NSString alloc] initWithData:pickled encoding:NSUTF8StringEncoding];
+    [pickled resetBytesInRange:NSMakeRange(0, pickled.length)];
     return pickleString;
 }
 
diff --git a/xcode/OLMKit/OLMInboundGroupSession.m b/xcode/OLMKit/OLMInboundGroupSession.m
index 68750ec..9e57741 100644
--- a/xcode/OLMKit/OLMInboundGroupSession.m
+++ b/xcode/OLMKit/OLMInboundGroupSession.m
@@ -227,6 +227,7 @@
     }
     NSMutableData *pickle = [serializedData dataUsingEncoding:NSUTF8StringEncoding].mutableCopy;
     size_t result = olm_unpickle_inbound_group_session(session, key.bytes, key.length, pickle.mutableBytes, pickle.length);
+    [pickle resetBytesInRange:NSMakeRange(0, pickle.length)];
     if (result == olm_error()) {
         const char *olm_error = olm_inbound_group_session_last_error(session);
         NSString *errorString = [NSString stringWithUTF8String:olm_error];
@@ -253,6 +254,7 @@
         return nil;
     }
     NSString *pickleString = [[NSString alloc] initWithData:pickled encoding:NSUTF8StringEncoding];
+    [pickled resetBytesInRange:NSMakeRange(0, pickled.length)];
     return pickleString;
 }
 
diff --git a/xcode/OLMKit/OLMOutboundGroupSession.m b/xcode/OLMKit/OLMOutboundGroupSession.m
index a3421fd..a0a7cc6 100644
--- a/xcode/OLMKit/OLMOutboundGroupSession.m
+++ b/xcode/OLMKit/OLMOutboundGroupSession.m
@@ -148,6 +148,7 @@
     }
     NSMutableData *pickle = [serializedData dataUsingEncoding:NSUTF8StringEncoding].mutableCopy;
     size_t result = olm_unpickle_outbound_group_session(session, key.bytes, key.length, pickle.mutableBytes, pickle.length);
+    [pickle resetBytesInRange:NSMakeRange(0, pickle.length)];
     if (result == olm_error()) {
         const char *olm_error = olm_outbound_group_session_last_error(session);
         NSString *errorString = [NSString stringWithUTF8String:olm_error];
@@ -174,6 +175,7 @@
         return nil;
     }
     NSString *pickleString = [[NSString alloc] initWithData:pickled encoding:NSUTF8StringEncoding];
+    [pickled resetBytesInRange:NSMakeRange(0, pickled.length)];
     return pickleString;
 }
 
diff --git a/xcode/OLMKit/OLMSession.m b/xcode/OLMKit/OLMSession.m
index 8c29113..fc58a08 100644
--- a/xcode/OLMKit/OLMSession.m
+++ b/xcode/OLMKit/OLMSession.m
@@ -309,6 +309,7 @@
     }
     NSMutableData *pickle = [serializedData dataUsingEncoding:NSUTF8StringEncoding].mutableCopy;
     size_t result = olm_unpickle_session(_session, key.bytes, key.length, pickle.mutableBytes, pickle.length);
+    [pickle resetBytesInRange:NSMakeRange(0, pickle.length)];
     if (result == olm_error()) {
         const char *olm_error = olm_session_last_error(_session);
         NSString *errorString = [NSString stringWithUTF8String:olm_error];
@@ -335,6 +336,7 @@
         return nil;
     }
     NSString *pickleString = [[NSString alloc] initWithData:pickled encoding:NSUTF8StringEncoding];
+    [pickled resetBytesInRange:NSMakeRange(0, pickled.length)];
     return pickleString;
 }