diff --git a/src/proto.h b/src/proto.h
index 1d9ba95d..14eeadf1 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -668,9 +668,6 @@ void set_modified(void);
 void statusbar(const char *msg, ...);
 void bottombars(const shortcut *s);
 void onekey(const char *keystroke, const char *desc, size_t len);
-#ifndef NDEBUG
-int check_linenumbers(const filestruct *fileptr);
-#endif
 size_t get_page_start(size_t column);
 void reset_cursor(void);
 void edit_add(const filestruct *fileptr, const char *converted, int
@@ -693,6 +690,9 @@ size_t help_line_len(const char *ptr);
 void do_help(void);
 #endif
 void do_replace_highlight(bool highlight_flag, const char *word);
+#ifndef NDEBUG
+int check_linenumbers(const filestruct *fileptr);
+#endif
 #ifdef DEBUG
 void dump_buffer(const filestruct *inptr);
 void dump_buffer_reverse(void);
diff --git a/src/winio.c b/src/winio.c
index eb706117..22128bd6 100644
--- a/src/winio.c
+++ b/src/winio.c
@@ -2969,19 +2969,6 @@ void onekey(const char *keystroke, const char *desc, size_t len)
     }
 }
 
-/* And so start the display update routines. */
-#ifndef NDEBUG
-int check_linenumbers(const filestruct *fileptr)
-{
-    int check_line = 0;
-    const filestruct *filetmp;
-
-    for (filetmp = edittop; filetmp != fileptr; filetmp = filetmp->next)
-	check_line++;
-    return check_line;
-}
-#endif
-
 /* nano scrolls horizontally within a line in chunks.  This function
  * returns the column number of the first character displayed in the
  * window when the cursor is at the given column.  Note that
@@ -3979,6 +3966,21 @@ void do_replace_highlight(bool highlight_flag, const char *word)
 	wattroff(edit, A_REVERSE);
 }
 
+#ifndef NDEBUG
+/* Return what the current line number should be, starting at edittop
+ * and ending at fileptr. */
+int check_linenumbers(const filestruct *fileptr)
+{
+    int check_line = 0;
+    const filestruct *filetmp;
+
+    for (filetmp = edittop; filetmp != fileptr; filetmp = filetmp->next)
+	check_line++;
+
+    return check_line;
+}
+#endif
+
 #ifdef DEBUG
 /* Dump the passed-in file structure to stderr. */
 void dump_buffer(const filestruct *inptr)