diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index e69ff8e4f42..7acc4c6c2fd 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2018-06-07  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/86045
+	* simplify.c (gfc_simplify_mod): Re-arrange code to test whether
+	'P' is zero and issue an error if it is.
+
 2018-06-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/85641
diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index fdd85edf62c..41997367cf9 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -5473,41 +5473,46 @@ gfc_simplify_mod (gfc_expr *a, gfc_expr *p)
   gfc_expr *result;
   int kind;
 
-  if (a->expr_type != EXPR_CONSTANT || p->expr_type != EXPR_CONSTANT)
+  /* First check p.  */
+  if (p->expr_type != EXPR_CONSTANT)
+    return NULL;
+
+  /* p shall not be 0.  */
+  switch (p->ts.type)
+    {
+      case BT_INTEGER:
+	if (mpz_cmp_ui (p->value.integer, 0) == 0)
+	  {
+	    gfc_error ("Argument %qs of MOD at %L shall not be zero",
+			"P", &p->where);
+	    return &gfc_bad_expr;
+	  }
+	break;
+      case BT_REAL:
+	if (mpfr_cmp_ui (p->value.real, 0) == 0)
+	  {
+	    gfc_error ("Argument %qs of MOD at %L shall not be zero",
+			"P", &p->where);
+	    return &gfc_bad_expr;
+	  }
+	break;
+      default:
+	gfc_internal_error ("gfc_simplify_mod(): Bad arguments");
+    }
+
+  if (a->expr_type != EXPR_CONSTANT)
     return NULL;
 
   kind = a->ts.kind > p->ts.kind ? a->ts.kind : p->ts.kind;
   result = gfc_get_constant_expr (a->ts.type, kind, &a->where);
 
-  switch (a->ts.type)
+  if (a->ts.type == BT_INTEGER)
+    mpz_tdiv_r (result->value.integer, a->value.integer, p->value.integer);
+  else
     {
-      case BT_INTEGER:
-	if (mpz_cmp_ui (p->value.integer, 0) == 0)
-	  {
-	    /* Result is processor-dependent.  */
-	    gfc_error ("Second argument MOD at %L is zero", &a->where);
-	    gfc_free_expr (result);
-	    return &gfc_bad_expr;
-	  }
-	mpz_tdiv_r (result->value.integer, a->value.integer, p->value.integer);
-	break;
-
-      case BT_REAL:
-	if (mpfr_cmp_ui (p->value.real, 0) == 0)
-	  {
-	    /* Result is processor-dependent.  */
-	    gfc_error ("Second argument of MOD at %L is zero", &p->where);
-	    gfc_free_expr (result);
-	    return &gfc_bad_expr;
-	  }
-
-	gfc_set_model_kind (kind);
-	mpfr_fmod (result->value.real, a->value.real, p->value.real,
-		   GFC_RND_MODE);
-	break;
-
-      default:
-	gfc_internal_error ("gfc_simplify_mod(): Bad arguments");
+      gfc_set_model_kind (kind);
+      mpfr_fmod (result->value.real, a->value.real, p->value.real,
+		 GFC_RND_MODE);
     }
 
   return range_check (result, "MOD");
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 691d233e3b7..f26dd5b2f58 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-06-07  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/86045
+	* gfortran.dg/pr86045.f90: New test.
+
 2018-06-07  Marek Polacek  <polacek@redhat.com>
 
 	* g++.dg/cpp0x/range-for9.C: Adjust dg-error.
diff --git a/gcc/testsuite/gfortran.dg/pr86045.f90 b/gcc/testsuite/gfortran.dg/pr86045.f90
new file mode 100644
index 00000000000..685672f1dbd
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr86045.f90
@@ -0,0 +1,7 @@
+! { dg-do compile }
+program p
+   logical :: a(2) = (mod([2,3],0) == 0)     ! { dg-error "shall not be zero" }
+   integer :: b = count(mod([2,3],0) == 0)   ! { dg-error "shall not be zero" }
+   integer :: c = all(mod([2,3],0) == 0)     ! { dg-error "shall not be zero" }
+   integer :: d = any(mod([2,3],0) == 0)     ! { dg-error "shall not be zero" }
+end