diff -ur a/bash/builtins/common.h b/bash/builtins/common.h
--- a/bash/builtins/common.h	2010-05-31 00:31:51.000000000 +0200
+++ b/bash/builtins/common.h	2014-09-16 21:36:20.139826595 +0200
@@ -33,6 +33,8 @@
 #define SEVAL_RESETLINE	0x010
 #define SEVAL_PARSEONLY	0x020
 #define SEVAL_NOLONGJMP 0x040
+#define SEVAL_FUNCDEF	0x080		/* only allow function definitions */
+#define SEVAL_ONECMD	0x100		/* only allow a single command */
 
 /* Flags for describe_command, shared between type.def and command.def */
 #define CDESC_ALL		0x001	/* type -a */
diff -ur a/bash/builtins/evalstring.c b/bash/builtins/evalstring.c
--- a/bash/builtins/evalstring.c	2010-11-23 14:22:15.000000000 +0100
+++ b/bash/builtins/evalstring.c	2014-09-16 21:36:20.139826595 +0200
@@ -261,6 +261,14 @@
 	    {
 	      struct fd_bitmap *bitmap;
 
+	      if ((flags & SEVAL_FUNCDEF) && command->type != cm_function_def)
+		{
+		  internal_warning ("%s: ignoring function definition attempt", from_file);
+		  should_jump_to_top_level = 0;
+		  last_result = last_command_exit_value = EX_BADUSAGE;
+		  break;
+		}
+
 	      bitmap = new_fd_bitmap (FD_BITMAP_SIZE);
 	      begin_unwind_frame ("pe_dispose");
 	      add_unwind_protect (dispose_fd_bitmap, bitmap);
@@ -321,6 +329,9 @@
 	      dispose_command (command);
 	      dispose_fd_bitmap (bitmap);
 	      discard_unwind_frame ("pe_dispose");
+
+	      if (flags & SEVAL_ONECMD)
+		break;
 	    }
 	}
       else
diff -ur a/bash/variables.c b/bash/variables.c
--- a/bash/variables.c	2014-09-16 21:35:34.878850652 +0200
+++ b/bash/variables.c	2014-09-16 21:37:16.221034763 +0200
@@ -347,7 +347,11 @@
 	  temp_string[char_index] = ' ';
 	  strcpy (temp_string + char_index + 1, string);
 
-	  parse_and_execute (temp_string, name, SEVAL_NONINT|SEVAL_NOHIST);
+ 	  /* Don't import function names that are invalid identifiers from the
+ 	     environment, though we still allow them to be defined as shell
+ 	     variables. */
+ 	  if (legal_identifier (name))
+ 	    parse_and_execute (temp_string, name, SEVAL_NONINT|SEVAL_NOHIST|SEVAL_FUNCDEF|SEVAL_ONECMD);
 
 	  /* Ancient backwards compatibility.  Old versions of bash exported
 	     functions like name()=() {...} */
@@ -361,10 +365,6 @@
 	    }
 	  else
 	    report_error (_("error importing function definition for `%s'"), name);
-
-	  /* ( */
-	  if (name[char_index - 1] == ')' && name[char_index - 2] == '\0')
-	    name[char_index - 2] = '(';		/* ) */
 	}
 #if defined (ARRAY_VARS)
 #  if 0