diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index a62a3bb642d..2301724729f 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -6505,10 +6505,21 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 		    {
 		      gfc_conv_expr_reference (&parmse, e);
 
-		      if (fsym
-			  && fsym->attr.intent == INTENT_OUT
-			  && !fsym->attr.allocatable
-			  && !fsym->attr.pointer
+		      gfc_symbol *dsym = fsym;
+		      gfc_dummy_arg *dummy;
+
+		      /* Use associated dummy as fallback for formal
+			 argument if there is no explicit interface.  */
+		      if (dsym == NULL
+			  && (dummy = arg->associated_dummy)
+			  && dummy->intrinsicness == GFC_NON_INTRINSIC_DUMMY_ARG
+			  && dummy->u.non_intrinsic->sym)
+			dsym = dummy->u.non_intrinsic->sym;
+
+		      if (dsym
+			  && dsym->attr.intent == INTENT_OUT
+			  && !dsym->attr.allocatable
+			  && !dsym->attr.pointer
 			  && e->expr_type == EXPR_VARIABLE
 			  && e->ref == NULL
 			  && e->symtree
diff --git a/gcc/testsuite/gfortran.dg/intent_optimize_4.f90 b/gcc/testsuite/gfortran.dg/intent_optimize_4.f90
new file mode 100644
index 00000000000..2f184bf84a8
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/intent_optimize_4.f90
@@ -0,0 +1,24 @@
+! { dg-do run }
+! { dg-additional-options "-fno-inline -fno-ipa-modref -fdump-tree-optimized -fdump-tree-original" }
+!
+! PR fortran/105012
+! Check that the INTENT(OUT) attribute causes one clobber to be emitted in
+! the caller before the call to Y in the *.original dump, and the
+! initialization constant to be optimized away in the *.optimized dump,
+! despite the non-explicit interface if the subroutine with the INTENT(OUT)
+! is declared in the same file.
+
+SUBROUTINE Y (Z)
+      integer, intent(out) :: Z
+      Z = 42
+END SUBROUTINE Y
+PROGRAM TEST
+    integer :: X
+    X = 123456789
+    CALL Y (X)
+    if (X.ne.42) STOP 1
+END PROGRAM
+
+! { dg-final { scan-tree-dump-times "CLOBBER" 1 "original" } }
+! { dg-final { scan-tree-dump "x = {CLOBBER};" "original" } }
+! { dg-final { scan-tree-dump-not "123456789" "optimized" { target __OPTIMIZE__ } } }