diff --git a/src/hasp/hasp_utilities.cpp b/src/hasp/hasp_utilities.cpp
index 3cdd6386..75ab5cd8 100644
--- a/src/hasp/hasp_utilities.cpp
+++ b/src/hasp/hasp_utilities.cpp
@@ -31,4 +31,20 @@ bool hasp_util_is_only_digits(const char * s)
         digits++;
     }
     return strlen(s) == digits;
+}
+
+int hasp_util_format_bytes(size_t filesize, char * buf, size_t len)
+{
+    if(filesize < 1024) return snprintf_P(buf, len, PSTR("%d B"), filesize);
+
+    char labels[] = "kMGT";
+    filesize      = filesize * 10 / 1024; // multiply by 10 for 1 decimal place
+    int unit      = 0;
+
+    while(filesize >= 10240 && unit < sizeof(labels) - 1) { // it is multiplied by 10
+        unit++;
+        filesize = filesize / 1024;
+    }
+
+    return snprintf_P(buf, len, PSTR("%d.%d %ciB"), filesize / 10, filesize % 10, labels[unit]);
 }
\ No newline at end of file
diff --git a/src/hasp/hasp_utilities.h b/src/hasp/hasp_utilities.h
index fa99fe24..eb164cd5 100644
--- a/src/hasp/hasp_utilities.h
+++ b/src/hasp/hasp_utilities.h
@@ -7,5 +7,6 @@
 uint16_t hasp_util_get_sdbm(const char * str);
 bool hasp_util_is_true(const char * s);
 bool hasp_util_is_only_digits(const char * s);
+int hasp_util_format_bytes(size_t filesize, char * buf, size_t len);
 
 #endif
\ No newline at end of file
diff --git a/src/hasp_hal.cpp b/src/hasp_hal.cpp
index 41028806..aa0323d0 100644
--- a/src/hasp_hal.cpp
+++ b/src/hasp_hal.cpp
@@ -293,26 +293,7 @@ uint16_t halGetCpuFreqMHz()
 #endif
 }
 
-String halFormatBytes(size_t bytes)
-{
-    String output((char *)0);
-    output.reserve(128);
 
-    if(bytes < 1024) {
-        output += bytes;
-    } else if(bytes < (1024 * 1024)) {
-        output += bytes / 1024.0;
-        output += "K";
-    } else if(bytes < (1024 * 1024 * 1024)) {
-        output += bytes / 1024.0 / 1024.0;
-        output += "M";
-    } else {
-        output += bytes / 1024.0 / 1024.0 / 1024.0;
-        output += "G";
-    }
-    output += "B";
-    return output;
-}
 
 String halDisplayDriverName()
 {
diff --git a/src/hasp_hal.h b/src/hasp_hal.h
index e5163633..5c735bab 100644
--- a/src/hasp_hal.h
+++ b/src/hasp_hal.h
@@ -15,7 +15,6 @@ String halGetCoreVersion(void);
 String halGetChipModel();
 String halGetMacAddress(int start, const char * seperator);
 uint16_t halGetCpuFreqMHz(void);
-String halFormatBytes(size_t bytes);
 String halDisplayDriverName(void);
 String halGpioName(uint8_t gpio);