diff --git a/Core/apu.c b/Core/apu.c
index 7454e26fc..84bed5da5 100644
--- a/Core/apu.c
+++ b/Core/apu.c
@@ -1854,18 +1854,20 @@ int GB_start_audio_recording(GB_gameboy_t *gb, const char *path, GB_audio_format
         case GB_AUDIO_FORMAT_AIFF: {
             aiff_header_t header = {0,};
             if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
+                int ret = errno ?: EIO;
                 fclose(gb->apu_output.output_file);
                 gb->apu_output.output_file = NULL;
-                return errno;
+                return ret;
             }
             return 0;
         }
         case GB_AUDIO_FORMAT_WAV: {
             wav_header_t header = {0,};
             if (fwrite(&header, sizeof(header), 1, gb->apu_output.output_file) != 1) {
+                int ret = errno ?: EIO;
                 fclose(gb->apu_output.output_file);
                 gb->apu_output.output_file = NULL;
-                return errno;
+                return ret;
             }
             return 0;
         }
diff --git a/Core/cheats.c b/Core/cheats.c
index b3bc2e7b6..cf2a69054 100644
--- a/Core/cheats.c
+++ b/Core/cheats.c
@@ -338,7 +338,6 @@ int GB_save_cheats(GB_gameboy_t *gb, const char *path)
         }
     }
     
-    errno = 0;
     fclose(f);
-    return errno;
+    return 0;
 }
diff --git a/Core/gb.c b/Core/gb.c
index fafe6cd17..c4398d3b2 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -15,6 +15,7 @@
 
 void GB_attributed_logv(GB_gameboy_t *gb, GB_log_attributes_t attributes, const char *fmt, va_list args)
 {
+    int errno_backup = errno;
     char *string = NULL;
     vasprintf(&string, fmt, args);
     if (string) {
@@ -27,6 +28,7 @@ void GB_attributed_logv(GB_gameboy_t *gb, GB_log_attributes_t attributes, const
         }
     }
     free(string);
+    errno = errno_backup;
 }
 
 void GB_attributed_log(GB_gameboy_t *gb, GB_log_attributes_t attributes, const char *fmt, ...)
@@ -877,8 +879,7 @@ int GB_save_battery_to_buffer(GB_gameboy_t *gb, uint8_t *buffer, size_t size)
         memcpy(buffer + gb->mbc_ram_size, &rtc_save.vba64, sizeof(rtc_save.vba64));
     }
 
-    errno = 0;
-    return errno;
+    return 0;
 }
 
 int GB_save_battery(GB_gameboy_t *gb, const char *path)
@@ -942,9 +943,8 @@ int GB_save_battery(GB_gameboy_t *gb, const char *path)
 
     }
 
-    errno = 0;
     fclose(f);
-    return errno;
+    return 0;
 }
 
 static void load_tpp1_save_data(GB_gameboy_t *gb, const tpp1_rtc_save_t *data)
diff --git a/Core/save_state.c b/Core/save_state.c
index be725a474..8a9a467e1 100644
--- a/Core/save_state.c
+++ b/Core/save_state.c
@@ -834,9 +834,8 @@ static int save_state_internal(GB_gameboy_t *gb, virtual_file_t *file, bool appe
         goto error;
     }
     
-    errno = 0;
 error:
-    return errno;
+    return 0;
 }
 
 int GB_save_state(GB_gameboy_t *gb, const char *path)