Index: gcc/fortran/simplify.c
===================================================================
--- gcc/fortran/simplify.c	(revision 258006)
+++ gcc/fortran/simplify.c	(working copy)
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gfortran.h"
 #include "arith.h"
 #include "intrinsic.h"
+#include "match.h"
 #include "target-memory.h"
 #include "constructor.h"
 #include "version.h"	/* For version_string.  */
@@ -7370,10 +7371,12 @@ gfc_simplify_transfer (gfc_expr *source, gfc_expr *mol
   unsigned char *buffer;
   size_t result_length;
 
+  if (!gfc_is_constant_expr (source) || !gfc_is_constant_expr (size))
+    return NULL;
 
-  if (!gfc_is_constant_expr (source)
-	|| (gfc_init_expr_flag && !gfc_is_constant_expr (mold))
-	|| !gfc_is_constant_expr (size))
+  if (!gfc_resolve_expr (mold))
+    return NULL;
+  if (gfc_init_expr_flag && !gfc_is_constant_expr (mold))
     return NULL;
 
   if (!gfc_calculate_transfer_sizes (source, mold, size, &source_size,
Index: gcc/testsuite/gfortran.dg/pr51434.f90
===================================================================
--- gcc/testsuite/gfortran.dg/pr51434.f90	(nonexistent)
+++ gcc/testsuite/gfortran.dg/pr51434.f90	(working copy)
@@ -0,0 +1,19 @@
+! { dg-do run }
+! PR fortran/51434
+module foo
+   implicit none
+   integer, parameter :: n = 5
+   character(len=1), parameter :: s(n) = 'a'
+   type :: a
+      integer :: m = n
+      character(len=1):: t(n) = transfer('abcde             ', s)
+   end type a
+end module foo
+
+program bar
+   use foo
+   implicit none
+   type(a) c
+   if (c%m /= n) stop 1
+   if (any(c%t /= ['a', 'b', 'c', 'd', 'e'])) stop 2
+end program bar