diff --git a/src/globals.h b/src/globals.h
index 4ca3092..5495eac 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -288,6 +288,9 @@
 #define SOURCING_LNUM (((estack_T *)exestack.ga_data)[exestack.ga_len - 1].es_lnum)
 
 #ifdef FEAT_EVAL
+// whether inside compile_def_function()
+EXTERN int	estack_compiling INIT(= FALSE);
+
 EXTERN int	ex_nesting_level INIT(= 0);	// nesting level
 EXTERN int	debug_break_level INIT(= -1);	// break below this level
 EXTERN int	debug_did_msg INIT(= FALSE);	// did "debug mode" message