diff --git a/src/hci/commands/nvo_cmd.c b/src/hci/commands/nvo_cmd.c
index b3775d09..f255bbf5 100644
--- a/src/hci/commands/nvo_cmd.c
+++ b/src/hci/commands/nvo_cmd.c
@@ -213,15 +213,19 @@ static int read_value ( const char *name, char **args __unused, char **value ) {
 
 	/* Read existing value */
 	if ( ( rc = fetchf_named_setting_copy ( name, &existing ) ) < 0 )
-		return rc;
+		goto err_existing;
 
 	/* Read new value */
-	*value = readline_history ( NULL, existing, NULL );
+	if ( ( rc = readline_history ( NULL, existing, NULL, value ) ) != 0 )
+		goto err_new;
 
-	/* Free existing value */
+	/* Success */
+	rc = 0;
+
+ err_new:
 	free ( existing );
-
-	return 0;
+ err_existing:
+	return rc;
 }
 
 /**
diff --git a/src/hci/readline.c b/src/hci/readline.c
index a199fb0e..d67980b2 100644
--- a/src/hci/readline.c
+++ b/src/hci/readline.c
@@ -22,6 +22,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <errno.h>
 #include <ipxe/console.h>
 #include <ipxe/keys.h>
 #include <ipxe/editstring.h>
@@ -244,18 +245,22 @@ void history_free ( struct readline_history *history ) {
  * @v prefill		Prefill string, or NULL for no prefill
  * @v history		History buffer, or NULL for no history
  * @ret line		Line read from console (excluding terminating newline)
+ * @ret rc		Return status code
  *
  * The returned line is allocated with malloc(); the caller must
  * eventually call free() to release the storage.
  */
-char * readline_history ( const char *prompt, const char *prefill,
-			  struct readline_history *history ) {
+int readline_history ( const char *prompt, const char *prefill,
+		       struct readline_history *history, char **line ) {
 	char buf[READLINE_MAX];
 	struct edit_string string;
 	int key;
 	int move_by;
 	const char *new_string;
-	char *line;
+	int rc;
+
+	/* Avoid returning uninitialised data on error */
+	*line = NULL;
 
 	/* Display prompt, if applicable */
 	if ( prompt )
@@ -280,12 +285,11 @@ char * readline_history ( const char *prompt, const char *prefill,
 		switch ( key ) {
 		case CR:
 		case LF:
-			line = strdup ( buf );
-			if ( ! line )
-				printf ( "\nOut of memory" );
+			*line = strdup ( buf );
+			rc = ( ( *line ) ? 0 : -ENOMEM );
 			goto done;
 		case CTRL_C:
-			line = NULL;
+			rc = -ECANCELED;
 			goto done;
 		case KEY_UP:
 			move_by = 1;
@@ -311,11 +315,12 @@ char * readline_history ( const char *prompt, const char *prefill,
  done:
 	putchar ( '\n' );
 	if ( history ) {
-		if ( line && line[0] )
-			history_append ( history, line );
+		if ( *line && (*line)[0] )
+			history_append ( history, *line );
 		history_cleanup ( history );
 	}
-	return line;
+	assert ( ( rc == 0 ) ^ ( *line == NULL ) );
+	return rc;
 }
 
 /**
@@ -328,5 +333,8 @@ char * readline_history ( const char *prompt, const char *prefill,
  * eventually call free() to release the storage.
  */
 char * readline ( const char *prompt ) {
-	return readline_history ( prompt, NULL, NULL );
+	char *line;
+
+	readline_history ( prompt, NULL, NULL, &line );
+	return line;
 }
diff --git a/src/hci/shell.c b/src/hci/shell.c
index f4cf9bc8..b6208676 100644
--- a/src/hci/shell.c
+++ b/src/hci/shell.c
@@ -86,7 +86,7 @@ int shell ( void ) {
 
 	/* Read and execute commands */
 	do {
-		line = readline_history ( shell_prompt, NULL, &history );
+		readline_history ( shell_prompt, NULL, &history, &line );
 		if ( line ) {
 			rc = system ( line );
 			free ( line );
diff --git a/src/include/ipxe/errfile.h b/src/include/ipxe/errfile.h
index dd63225d..514e1f8a 100644
--- a/src/include/ipxe/errfile.h
+++ b/src/include/ipxe/errfile.h
@@ -264,6 +264,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_ocsp		      ( ERRFILE_OTHER | 0x002f0000 )
 #define ERRFILE_nslookup	      ( ERRFILE_OTHER | 0x00300000 )
 #define ERRFILE_efi_snp_hii	      ( ERRFILE_OTHER | 0x00310000 )
+#define ERRFILE_readline	      ( ERRFILE_OTHER | 0x00320000 )
 
 /** @} */
 
diff --git a/src/include/readline/readline.h b/src/include/readline/readline.h
index 8b159975..0449a3f9 100644
--- a/src/include/readline/readline.h
+++ b/src/include/readline/readline.h
@@ -50,9 +50,8 @@ struct readline_history {
 };
 
 extern void history_free ( struct readline_history *history );
-extern char * __malloc readline_history ( const char *prompt,
-					  const char *prefill,
-					  struct readline_history *history );
+extern int readline_history ( const char *prompt, const char *prefill,
+			      struct readline_history *history, char **line );
 extern char * __malloc readline ( const char *prompt );
 
 #endif /* _READLINE_H */