Index: gcc/fortran/parse.c
===================================================================
--- gcc/fortran/parse.c	(revision 223094)
+++ gcc/fortran/parse.c	(working copy)
@@ -2425,8 +2425,7 @@ verify_st_order (st_state *p, gfc_statem
       break;
 
     default:
-      gfc_internal_error ("Unexpected %s statement in verify_st_order() at %C",
-			  gfc_ascii_statement (st));
+      return false;
     }
 
   /* All is well, record the statement in case we need it next time.  */
Index: gcc/testsuite/gfortran.dg/misplaced_statement.f90
===================================================================
--- gcc/testsuite/gfortran.dg/misplaced_statement.f90	(revision 0)
+++ gcc/testsuite/gfortran.dg/misplaced_statement.f90	(working copy)
@@ -0,0 +1,20 @@
+!{ dg-do compile }
+! PR fortran/66040
+!
+! Original code from Gerhard Steinmetz
+! <gerhard dot steinmetz dot fortran at t-online dot de>
+real function f1(x)
+   sequence          ! { dg-error "Unexpected SEQUENCE statement" }
+end function f1
+
+real function f2()
+   else              ! { dg-error "Unexpected ELSE statement" }
+end function f2
+
+real function f3()
+   block data        ! { dg-error "Unexpected BLOCK DATA statement" }
+end function f3
+
+real function f4()
+   program p         ! { dg-error "Unexpected PROGRAM statement" }
+end function f4