diff --git a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
index 7e73495..43c5645 100644
--- a/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
+++ b/src/objective-c/GRPCClient/private/GRPCWrappedCall.m
@@ -215,11 +215,15 @@
       __weak typeof(self) weakSelf = self;
       _handler = ^{
         __strong typeof(self) strongSelf = weakSelf;
-        NSError *error = [NSError grpc_errorFromStatusCode:strongSelf->_statusCode
-                                                   details:(char*)GRPC_SLICE_START_PTR(strongSelf->_details)];
-        NSDictionary *trailers = [NSDictionary
-                                  grpc_dictionaryFromMetadataArray:strongSelf->_trailers];
-        handler(error, trailers);
+        if (strongSelf) {
+          char *details = grpc_slice_to_c_string(strongSelf->_details);
+          NSError *error = [NSError grpc_errorFromStatusCode:strongSelf->_statusCode
+                                                     details:details];
+          NSDictionary *trailers = [NSDictionary
+                                    grpc_dictionaryFromMetadataArray:strongSelf->_trailers];
+          handler(error, trailers);
+          gpr_free(details);
+        }
       };
     }
   }
diff --git a/src/objective-c/GRPCClient/private/NSDictionary+GRPC.m b/src/objective-c/GRPCClient/private/NSDictionary+GRPC.m
index f834fef..feb2bb5 100644
--- a/src/objective-c/GRPCClient/private/NSDictionary+GRPC.m
+++ b/src/objective-c/GRPCClient/private/NSDictionary+GRPC.m
@@ -88,8 +88,10 @@
 + (instancetype)grpc_dictionaryFromMetadata:(grpc_metadata *)entries count:(size_t)count {
   NSMutableDictionary *metadata = [NSMutableDictionary dictionaryWithCapacity:count];
   for (grpc_metadata *entry = entries; entry < entries + count; entry++) {
-    NSString *name = [NSString stringWithCString:(char*)GRPC_SLICE_START_PTR(entry->key)
+    char *key = grpc_slice_to_c_string(entry->key);
+    NSString *name = [NSString stringWithCString:key
                                         encoding:NSASCIIStringEncoding];
+    gpr_free(key);
     if (!name || metadata[name]) {
       // Log if name is nil?
       continue;