diff --git a/lib/std/fmt.zig b/lib/std/fmt.zig
index ad3b2d8452..df6aac2e21 100644
--- a/lib/std/fmt.zig
+++ b/lib/std/fmt.zig
@@ -1009,8 +1009,10 @@ pub fn formatBuf(
 }
 
 /// Print a float in scientific notation to the specified precision. Null uses full precision.
-/// It should be the case that every full precision, printed value can be re-parsed back to the
-/// same type unambiguously.
+/// For floats with less than 64 bits, it should be the case that every full precision, printed
+/// value can be re-parsed back to the same type unambiguously.
+///
+/// Floats with more than 64 are currently rounded, see https://github.com/ziglang/zig/issues/1181
 pub fn formatFloatScientific(
     value: anytype,
     options: FormatOptions,
@@ -1213,6 +1215,8 @@ pub fn formatFloatHexadecimal(
 
 /// Print a float of the format x.yyyyy where the number of y is specified by the precision argument.
 /// By default floats are printed at full precision (no rounding).
+///
+/// Floats with more than 64 bits are not yet supported, see https://github.com/ziglang/zig/issues/1181
 pub fn formatFloatDecimal(
     value: anytype,
     options: FormatOptions,