diff --git a/src/fsharp/MethodCalls.fs b/src/fsharp/MethodCalls.fs
index df06f0064a..61ce01d1af 100644
--- a/src/fsharp/MethodCalls.fs
+++ b/src/fsharp/MethodCalls.fs
@@ -1173,6 +1173,15 @@ let AdjustCallerArgForOptional tcFieldInit eCallerMemberName (infoReader: InfoRe
         if isOptCallerArg then errorR(Error(FSComp.SR.tcFormalArgumentIsNotOptional(), m))
         assignedArg
 
+    // For non-nullable, non-optional arguments no conversion is needed.
+    // We return precisely the assignedArg.  This also covers the case where there
+    // can be a lingering permitted type mismatch between caller argument and called argument, 
+    // specifically caller can by `byref` and called `outref`.  No coercion is inserted in the
+    // expression tree in this case. 
+    | NotOptional when not (isNullableTy g calledArgTy) -> 
+        if isOptCallerArg then errorR(Error(FSComp.SR.tcFormalArgumentIsNotOptional(), m))
+        assignedArg
+
     | _ ->
 
         let callerArgExpr2 = 
@@ -1183,7 +1192,7 @@ let AdjustCallerArgForOptional tcFieldInit eCallerMemberName (infoReader: InfoRe
                 if isNullableTy g calledArgTy then 
                     MakeNullableExprIfNeeded infoReader calledArgTy callerArgTy callerArgExpr m
                 else
-                    callerArgExpr
+                    failwith "unreachable" // see case above
             
             | CallerSide dfltVal -> 
                 let calledArgTy = calledArg.CalledArgumentType
diff --git a/tests/fsharp/tests.fs b/tests/fsharp/tests.fs
index 1a2be765dc..4958c84cbe 100644
--- a/tests/fsharp/tests.fs
+++ b/tests/fsharp/tests.fs
@@ -254,9 +254,20 @@ module CoreTests =
         begin
             use testOkFile = fileguard cfg "test.ok"
 
-            fsc cfg "%s -o:test.exe -g" cfg.fsc_flags ["test.fsx"]
+            fsc cfg "%s -o:test.exe -g --langversion:4.7" cfg.fsc_flags ["test.fsx"]
 
-            singleNegTest cfg "test"
+            singleVersionedNegTest cfg "4.7" "test"
+            exec cfg ("." ++ "test.exe") ""
+
+            testOkFile.CheckExists()
+        end
+
+        begin
+            use testOkFile = fileguard cfg "test.ok"
+
+            fsc cfg "%s -o:test.exe -g --langversion:5.0" cfg.fsc_flags ["test.fsx"]
+
+            singleVersionedNegTest cfg "5.0" "test"
 
             exec cfg ("." ++ "test.exe") ""