diff --git a/docs/changes.txt b/docs/changes.txt
index 283e3c0d4..a4a17bfd8 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -82,6 +82,7 @@
 - Fixed bug in grep out-of-memory workaround on Unit Test
 - Fixed bug in input_tokenizer when TOKEN_ATTR_FIXED_LENGTH is used and refactor modules
 - Fixed bug in --stdout that caused certain rules to malfunction
+- Fixed bug in --stdout when multiple computing devices are active
 - Fixed build failed for 10700 optimized with Apple Metal
 - Fixed build failed for 13772 and 13773 with Apple Metal
 - Fixed build failed for 18400 with Apple Metal
diff --git a/include/types.h b/include/types.h
index e6ea946f9..6b508d7f0 100644
--- a/include/types.h
+++ b/include/types.h
@@ -2122,6 +2122,8 @@ typedef struct outfile_ctx
 
   char   *filename;
 
+  hc_thread_mutex_t mux_outfile;
+
 } outfile_ctx_t;
 
 typedef struct pot
diff --git a/src/outfile.c b/src/outfile.c
index b14b56a7a..43ddb8611 100644
--- a/src/outfile.c
+++ b/src/outfile.c
@@ -15,6 +15,7 @@
 #include "backend.h"
 #include "shared.h"
 #include "locking.h"
+#include "thread.h"
 #include "outfile.h"
 
 u32 outfile_format_parse (const char *format_string)
@@ -506,6 +507,8 @@ int outfile_init (hashcat_ctx_t *hashcat_ctx)
   outfile_ctx->outfile_json    = user_options->outfile_json;
   outfile_ctx->is_fifo         = hc_path_is_fifo (outfile_ctx->filename);
 
+  hc_thread_mutex_init (outfile_ctx->mux_outfile);
+
   return 0;
 }
 
@@ -513,6 +516,8 @@ void outfile_destroy (hashcat_ctx_t *hashcat_ctx)
 {
   outfile_ctx_t *outfile_ctx = hashcat_ctx->outfile_ctx;
 
+  hc_thread_mutex_delete (outfile_ctx->mux_outfile);
+
   if (outfile_ctx->is_fifo == true && outfile_ctx->fp.pfp != NULL)
   {
     hc_unlockfile (&outfile_ctx->fp);
diff --git a/src/stdout.c b/src/stdout.c
index 429836793..127232d0e 100644
--- a/src/stdout.c
+++ b/src/stdout.c
@@ -12,6 +12,7 @@
 #include "mpsp.h"
 #include "backend.h"
 #include "shared.h"
+#include "thread.h"
 #include "stdout.h"
 
 static void out_flush (out_t *out)
@@ -59,6 +60,10 @@ int process_stdout (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param,
   straight_ctx_t   *straight_ctx   = hashcat_ctx->straight_ctx;
   user_options_t   *user_options   = hashcat_ctx->user_options;
 
+  // prevent wrong candidates in output when backend_ctx->backend_devices_active > 1
+
+  hc_thread_mutex_lock (outfile_ctx->mux_outfile);
+
   char *filename = outfile_ctx->filename;
 
   out_t out;
@@ -69,6 +74,8 @@ int process_stdout (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param,
     {
       event_log_error (hashcat_ctx, "%s: %s", filename, strerror (errno));
 
+      hc_thread_mutex_unlock (outfile_ctx->mux_outfile);
+
       return -1;
     }
 
@@ -78,6 +85,8 @@ int process_stdout (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param,
 
       event_log_error (hashcat_ctx, "%s: %s", filename, strerror (errno));
 
+      hc_thread_mutex_unlock (outfile_ctx->mux_outfile);
+
       return -1;
     }
   }
@@ -341,5 +350,7 @@ int process_stdout (hashcat_ctx_t *hashcat_ctx, hc_device_param_t *device_param,
     hc_fclose (&out.fp);
   }
 
+  hc_thread_mutex_unlock (outfile_ctx->mux_outfile);
+
   return rc;
 }