diff --git a/doc/api/buffer.markdown b/doc/api/buffer.markdown
index 0f42de73aaac6c..ce4fda84ea41b0 100644
--- a/doc/api/buffer.markdown
+++ b/doc/api/buffer.markdown
@@ -1398,7 +1398,7 @@ console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeDoubleBE()` writes big endian, `writeDoubleLE()` writes little
 endian). The `value` argument *should* be a valid 64-bit double. Behavior is
-unspecified if `value` is anything other than a 64-bit double.
+not defined when `value` is anything other than a 64-bit double.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
 that `value` may be too large for the specific function and `offset` may be
@@ -1430,7 +1430,7 @@ console.log(buf);
 
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeFloatBE()` writes big endian, `writeFloatLE()` writes little
-endian). Behavior is unspecified if `value` is anything other than a 32-bit
+endian). Behavior is not defined when `value` is anything other than a 32-bit
 float.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
@@ -1461,7 +1461,7 @@ console.log(buf);
 * Return: {Number} The offset plus the number of written bytes
 
 Writes `value` to the Buffer at the specified `offset`. The `value` should be a
-valid signed 8-bit integer.  Behavior is unspecified if `value` is anything
+valid signed 8-bit integer.  Behavior is not defined when `value` is anything
 other than a signed 8-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
@@ -1490,7 +1490,7 @@ console.log(buf);
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeInt16BE()` writes big endian, `writeInt16LE()` writes little
 endian). The `value` should be a valid signed 16-bit integer. Behavior is
-unspecified if `value` is anything other than a signed 16-bit integer.
+not defined when `value` is anything other than a signed 16-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
 that `value` may be too large for the specific function and `offset` may be
@@ -1518,7 +1518,7 @@ console.log(buf);
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeInt32BE()` writes big endian, `writeInt32LE()` writes little
 endian). The `value` should be a valid signed 32-bit integer. Behavior is
-unspecified if `value` is anything other than a signed 32-bit integer.
+not defined when `value` is anything other than a signed 32-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
 that `value` may be too large for the specific function and `offset` may be
@@ -1564,7 +1564,7 @@ that `value` may be too large for the specific function and `offset` may be
 beyond the end of the Buffer leading to the values being silently dropped. This
 should not be used unless you are certain of correctness.
 
-Behavior is unspecified if `value` is anything other than an integer.
+Behavior is not defined when `value` is anything other than an integer.
 
 ### buf.writeUInt8(value, offset[, noAssert])
 
@@ -1574,7 +1574,7 @@ Behavior is unspecified if `value` is anything other than an integer.
 * Return: {Number} The offset plus the number of written bytes
 
 Writes `value` to the Buffer at the specified `offset`. The `value` should be a
-valid unsigned 8-bit integer.  Behavior is unspecified if `value` is anything
+valid unsigned 8-bit integer.  Behavior is not defined when `value` is anything
 other than an unsigned 8-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
@@ -1606,7 +1606,7 @@ console.log(buf);
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeUInt16BE()` writes big endian, `writeUInt16LE()` writes little
 endian). The `value` should be a valid unsigned 16-bit integer. Behavior is
-unspecified if `value` is anything other than an unsigned 16-bit integer.
+not defined when `value` is anything other than an unsigned 16-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
 that `value` may be too large for the specific function and `offset` may be
@@ -1641,7 +1641,7 @@ console.log(buf);
 Writes `value` to the Buffer at the specified `offset` with specified endian
 format (`writeUInt32BE()` writes big endian, `writeUInt32LE()` writes little
 endian). The `value` should be a valid unsigned 32-bit integer. Behavior is
-unspecified if `value` is anything other than an unsigned 32-bit integer.
+not defined when `value` is anything other than an unsigned 32-bit integer.
 
 Set `noAssert` to true to skip validation of `value` and `offset`. This means
 that `value` may be too large for the specific function and `offset` may be
@@ -1687,7 +1687,7 @@ that `value` may be too large for the specific function and `offset` may be
 beyond the end of the Buffer leading to the values being silently dropped. This
 should not be used unless you are certain of correctness.
 
-Behavior is unspecified if `value` is anything other than an unsigned integer.
+Behavior is not defined when `value` is anything other than an unsigned integer.
 
 ## buffer.INSPECT_MAX_BYTES