diff --git a/Crashlytics/Shared/FIRCLSMachO/FIRCLSMachO.m b/Crashlytics/Shared/FIRCLSMachO/FIRCLSMachO.m
index afc6e922818..e2f17eb5547 100644
--- a/Crashlytics/Shared/FIRCLSMachO/FIRCLSMachO.m
+++ b/Crashlytics/Shared/FIRCLSMachO/FIRCLSMachO.m
@@ -352,7 +352,7 @@ struct FIRCLSMachOSlice FIRCLSMachOSliceWithHeader(void* machHeader) {
 
   return archInfo->name;
 #else
-  const char* archname = macho_arch_name_for_mach_header(NULL);
+  const char* archname = macho_arch_name_for_mach_header(slice->startAddress);
 
   if (!archname) {
     return "unknown";