diff --git a/expand.c b/expand.c
index 702152bd..bbbd6a70 100644
--- a/expand.c
+++ b/expand.c
@@ -341,7 +341,14 @@ variable_expand (line)
 		/* Look up the value of the variable.  */
 		end = index (beg, closeparen);
 		if (end == 0)
-		  return initialize_variable_output ();
+		  {
+		    /* Unterminated variable reference.  */
+		    if (reading_filename != 0)
+		      makefile_fatal (reading_filename, *reading_lineno_ptr,
+				      "unterminated variable reference");
+		    else
+		      fatal ("unterminated variable reference");
+		  }
 		o = reference_variable (o, beg, end - beg);
 	      }