diff --git a/include/fast_float/float_common.h b/include/fast_float/float_common.h
index 7d0a1ed..d146f6a 100644
--- a/include/fast_float/float_common.h
+++ b/include/fast_float/float_common.h
@@ -45,7 +45,7 @@ bool is_space(uint8_t c) {
 
 namespace {
 constexpr uint32_t max_digits = 768;
-
+constexpr uint32_t max_digit_without_overflow = 19;
 constexpr int32_t decimal_point_range = 2047;
 } // namespace
 
@@ -140,12 +140,10 @@ struct decimal {
   bool truncated;
   uint8_t digits[max_digits];
 
-  // generate a mantissa by truncating to 19 digits, this assumes
-  // that num_digits >= 19 (caller should check).
+  // Generates a mantissa by truncating to 19 digits; this function assumes
+  // that num_digits >= 19 (the caller is responsible for the check).
+  // This function should be reasonably fast.
   inline uint64_t to_truncated_mantissa() {
-    const int64_t max_digit_with_overflow = 19;
-    static_assert(9999999999999999999U < 0xffffffffffffffff, "cannot fit 19 digits in an uint64_t");
-    static_assert(max_digit_with_overflow < max_digits, "too few max_digits");
     uint64_t val; 
     // 8 first digits
     ::memcpy(&val, digits, sizeof(uint64_t));
@@ -158,15 +156,14 @@ struct decimal {
     val = (val & 0x00FF00FF00FF00FF) * 6553601 >> 16;
     uint32_t eight_digits_value = uint32_t((val & 0x0000FFFF0000FFFF) * 42949672960001 >> 32);
     mantissa = 100000000 * mantissa + eight_digits_value;
-    for(size_t i = 2*sizeof(uint64_t); i < max_digit_with_overflow; i++) {
+    for(uint32_t i = 2*sizeof(uint64_t); i < max_digit_without_overflow; i++) {
       mantissa = mantissa * 10 + digits[i]; // can be accelerated
     }
     return mantissa;
   }
-  // generate an exponent matching to_truncated_mantissa() 
-  inline int64_t to_truncated_exponent() {
-    const int64_t max_digit_with_overflow = 19;
-    return decimal_point - max_digit_with_overflow;
+  // Generate san exponent matching to_truncated_mantissa() 
+  inline int32_t to_truncated_exponent() {
+    return decimal_point - max_digit_without_overflow;
   }    
 
 };