diff --git a/Library/Convert.c b/Library/Convert.c
index 32814e0..eb53c5f 100644
--- a/Library/Convert.c
+++ b/Library/Convert.c
@@ -642,6 +642,24 @@ char *reverse(char *Buffer, int i, int j)
     return Buffer;
 }
 
+float sqrtf(float x)
+{
+    if (x < 0.0f)
+        return NAN;
+
+    if (x < 1e-7f)
+        return 0.0f;
+
+    float guess = x / 2.0f;
+    for (short i = 0; i < 10; i++)
+    {
+        if (guess == 0.0f)
+            return 0.0f;
+        guess = (guess + x / guess) / 2.0f;
+    }
+    return guess;
+}
+
 char *strtok(char *src, const char *delim)
 {
     static char *src1;
diff --git a/include/convert.h b/include/convert.h
index 4e7cfe1..21ae612 100644
--- a/include/convert.h
+++ b/include/convert.h
@@ -5,6 +5,8 @@
 extern "C"
 {
 #endif
+#define NAN (__builtin_nanf(""))
+
     int isdigit(int c);
     int isspace(int c);
     int isempty(char *str);
@@ -15,6 +17,8 @@ extern "C"
     void swap(char *x, char *y);
     char *reverse(char *Buffer, int i, int j);
 
+    float sqrtf(float x);
+
     void backspace(char s[]);
     void append(char s[], char n);