diff --git a/src/log.c b/src/log.c
index a93ec1f..6294fdd 100644
--- a/src/log.c
+++ b/src/log.c
@@ -42,6 +42,9 @@ void init_logging_session(uint8_t *name, uint8_t *key, struct chatlog *log)
     if (!log->log_on)
         return;
 
+    if (!valid_nick(name))
+        name = UNKNOWN_NAME;
+
     char *user_config_dir = get_user_config_dir();
     int path_len = strlen(user_config_dir) + strlen(CONFIGDIR) + strlen(name); 
 
diff --git a/src/misc_tools.c b/src/misc_tools.c
index 31ef296..f2f810a 100644
--- a/src/misc_tools.c
+++ b/src/misc_tools.c
@@ -202,6 +202,7 @@ int qsort_strcasecmp_hlpr(const void *nick1, const void *nick2)
 /* Returns 1 if nick is valid, 0 if not. A valid toxic nick:
       - cannot be empty
       - cannot start with a space
+      - must not contain a forward slash (for logfile naming purposes)
       - must not contain contiguous spaces */
 int valid_nick(uint8_t *nick)
 {
@@ -213,6 +214,8 @@ int valid_nick(uint8_t *nick)
     for (i = 0; nick[i]; ++i) {
         if (nick[i] == ' ' && nick[i+1] == ' ')
             return 0;
+        if (nick[i] == '/')
+            return 0;
     }
 
     return 1;