diff --git a/cores/esp8266/core_esp8266_noniso.c b/cores/esp8266/core_esp8266_noniso.c
index 0b53583fd..d5b9d82f2 100644
--- a/cores/esp8266/core_esp8266_noniso.c
+++ b/cores/esp8266/core_esp8266_noniso.c
@@ -148,7 +148,8 @@ char* ultoa(unsigned long value, char* result, int base) {
 }
 
 char * dtostrf(double number, signed char width, unsigned char prec, char *s) {
-
+    bool negative = false;
+    
     if (isnan(number)) {
         strcpy(s, "nan");
         return s;
@@ -158,14 +159,17 @@ char * dtostrf(double number, signed char width, unsigned char prec, char *s) {
         return s;
     }
 
-    if (number > 4294967040.0 || number < -4294967040.0) {
-        strcpy(s, "ovf");
-        return s;
-    }
     char* out = s;
+   
+    int fillme = width; // how many cells to fill for the integer part
+    if (prec > 0) {
+        fillme -= (prec+1);
+    } 
+   
     // Handle negative numbers
     if (number < 0.0) {
-        *out++ = '-';
+        negative = true;
+        fillme--;
         number = -number;
     }
 
@@ -173,39 +177,47 @@ char * dtostrf(double number, signed char width, unsigned char prec, char *s) {
     // I optimized out most of the divisions
     double rounding = 2.0;
     for (uint8_t i = 0; i < prec; ++i)
-        rounding *= 10.0;       
-    rounding = 1.0 / rounding;   
+        rounding *= 10.0;     
+    rounding = 1.0 / rounding; 
 
     number += rounding;
-
-    // Extract the integer part of the number and print it
-    unsigned long int_part = (unsigned long)number;
-    double remainder = number - (double)int_part;
-    out += sprintf(out, "%d", int_part);
-
-    // Print the decimal point, but only if there are digits beyond
-    if (prec > 0) {
-        *out++ = '.';
+   
+    // Figure out how big our number really is
+    double tenpow = 1.0;
+    int digitcount = 1;
+    while (number >= 10.0 * tenpow) {
+        tenpow *= 10.0;   
+        digitcount++;
     }
-    // make sure the string is terminated before mesuring it length
-    *out = 0;
-    // Reduce minimum width accordingly
-    width -= strlen(s);
-
-    // Print the digits after the decimal point
+   
+    number /= tenpow;
+    fillme -= digitcount;
+   
+    // Pad unused cells with spaces
+    while (fillme-- > 0) {
+        *out++ = ' ';
+    }
+    
+    // Handle negative sign
+    if (negative) *out++ = '-';
+   
+    // Print the digits, and if necessary, the decimal point
+    digitcount += prec;
     int8_t digit = 0;
-    while (prec-- > 0) {
-        remainder *= 10.0;
-        digit = (int8_t)remainder;
+    while (digitcount-- > 0) {       
+        digit = (int8_t)number;
         if (digit > 9) digit = 9; // insurance
         *out++ = (char)('0' | digit);
-        width--;
-        remainder -= digit;
+        if ((digitcount == prec) && (prec > 0)) {
+            *out++ = '.';
+        }   
+        number -= digit;
+        number *= 10.0;
     }
-    // add '0' to fill minimum width requirement
-    while (width-- > 0) *out++ = ' ';
+
     // make sure the string is terminated
     *out = 0;
     return s;
 }
 
+