diff --git a/src/codegen.cpp b/src/codegen.cpp
index f4defb8405fa8e4e03ee49a31d224c91e62b9004..2965c8e59345ae40e77bc4ce096200ebd1820070 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -2905,6 +2905,10 @@ static void do_code_gen(CodeGen *g) {
             if (param_type->id == TypeTableEntryIdPointer) {
                 // when https://github.com/andrewrk/zig/issues/82 is fixed, add
                 // non null attribute here
+
+                ///`i` is arg index + 1
+                ///I think that 0 is the return index, but it has a named LLVM constant variable
+                LLVMZigAddNonNullAttr(fn_table_entry->fn_value, param_decl_i + 1);
             }
             if (is_byval) {
                 // TODO
diff --git a/src/zig_llvm.cpp b/src/zig_llvm.cpp
index b0e32e8b6b999229d241ebdaea0029d330a11bbc..5749a996d505e75e4d777f332ea9e45f30837b87 100644
--- a/src/zig_llvm.cpp
+++ b/src/zig_llvm.cpp
@@ -140,6 +140,16 @@ LLVMValueRef LLVMZigBuildCall(LLVMBuilderRef B, LLVMValueRef Fn, LLVMValueRef *A
     return wrap(unwrap(B)->Insert(call_inst));
 }
 
+void LLVMZigAddNonNullAttr(LLVMValueRef fn, unsigned i)
+{
+    assert( isa<Function>(unwrap(fn)) );
+
+    Function *unwrapped_function = reinterpret_cast<Function*>(unwrap(fn));
+
+    unwrapped_function->addAttribute(i, Attribute::NonNull);
+}
+
+
 LLVMZigDIType *LLVMZigCreateDebugPointerType(LLVMZigDIBuilder *dibuilder, LLVMZigDIType *pointee_type,
         uint64_t size_in_bits, uint64_t align_in_bits, const char *name)
 {
diff --git a/src/zig_llvm.hpp b/src/zig_llvm.hpp
index 74b2499276158a80847edcbb3ac2499267eb3b36..d4e3548b70f5a9f22960a9cacba314b5cc88b63f 100644
--- a/src/zig_llvm.hpp
+++ b/src/zig_llvm.hpp
@@ -39,6 +39,7 @@ void LLVMZigOptimizeModule(LLVMTargetMachineRef targ_machine_ref, LLVMModuleRef
 LLVMValueRef LLVMZigBuildCall(LLVMBuilderRef B, LLVMValueRef Fn, LLVMValueRef *Args,
         unsigned NumArgs, unsigned CC, const char *Name);
 
+void LLVMZigAddNonNullAttr(LLVMValueRef fn, unsigned i);
 
 LLVMZigDIType *LLVMZigCreateDebugPointerType(LLVMZigDIBuilder *dibuilder, LLVMZigDIType *pointee_type,
         uint64_t size_in_bits, uint64_t align_in_bits, const char *name);