diff --git a/llvm/bindings/ocaml/llvm/llvm_ocaml.c b/llvm/bindings/ocaml/llvm/llvm_ocaml.c
--- a/llvm/bindings/ocaml/llvm/llvm_ocaml.c
+++ b/llvm/bindings/ocaml/llvm/llvm_ocaml.c
@@ -885,7 +885,7 @@
 
 /* llvalue -> string option */
 CAMLprim value llvm_get_mdstring(LLVMValueRef V) {
-  size_t Len;
+  unsigned Len;
   const char *CStr = LLVMGetMDString(V, &Len);
   return cstr_to_string_option(CStr, Len);
 }
diff --git a/llvm/bindings/ocaml/target/target_ocaml.c b/llvm/bindings/ocaml/target/target_ocaml.c
--- a/llvm/bindings/ocaml/target/target_ocaml.c
+++ b/llvm/bindings/ocaml/target/target_ocaml.c
@@ -314,8 +314,8 @@
   char *ErrorMessage;
 
   if(LLVMTargetMachineEmitToFile(TargetMachine_val(Machine), Module,
-                                 String_val(FileName), Int_val(FileType),
-                                 &ErrorMessage)) {
+                                 (char *)String_val(FileName),
+                                 Int_val(FileType), &ErrorMessage)) {
     llvm_raise(*caml_named_value("Llvm_target.Error"), ErrorMessage);
   }