diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index 4d7ba3027f..48415eba16 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -636,13 +636,13 @@ pub fn (s string) i64() i64 {
 // f32 returns the value of the string as f32 `'1.0'.f32() == f32(1)`.
 @[inline]
 pub fn (s string) f32() f32 {
-	return f32(strconv.atof64(s) or { 0 })
+	return f32(strconv.atof64(s, allow_extra_chars: true) or { 0 })
 }
 
 // f64 returns the value of the string as f64 `'1.0'.f64() == f64(1)`.
 @[inline]
 pub fn (s string) f64() f64 {
-	return strconv.atof64(s) or { 0 }
+	return strconv.atof64(s, allow_extra_chars: true) or { 0 }
 }
 
 // u8_array returns the value of the hex/bin string as u8 array.
diff --git a/vlib/strconv/atof.c.v b/vlib/strconv/atof.c.v
index c35aabbae6..dcbe35753b 100644
--- a/vlib/strconv/atof.c.v
+++ b/vlib/strconv/atof.c.v
@@ -114,6 +114,7 @@ enum ParserState {
 	pinf           // number is higher than +HUGE_VAL
 	minf           // number is lower than -HUGE_VAL
 	invalid_number // invalid number, used for '#@%^' for example
+	extra_char     // extra char after number
 }
 
 // parser tries to parse the given string into a number
@@ -218,6 +219,9 @@ fn parser(s string) (ParserState, PrepNumber) {
 	if i == 0 && s.len > 0 {
 		return ParserState.invalid_number, pn
 	}
+	if i != s.len {
+		return ParserState.extra_char, pn
+	}
 	return result, pn
 }
 
@@ -387,13 +391,19 @@ fn converter(mut pn PrepNumber) u64 {
 	return result
 }
 
+@[params]
+pub struct AtoF64Param {
+pub:
+	allow_extra_chars bool // allow extra characters after number
+}
+
 // atof64 parses the string `s`, and if possible, converts it into a f64 number
-pub fn atof64(s string) !f64 {
+pub fn atof64(s string, param AtoF64Param) !f64 {
 	if s.len == 0 {
 		return error('expected a number found an empty string')
 	}
 	mut res := Float64u{}
-	mut res_parsing, mut pn := parser(s)
+	res_parsing, mut pn := parser(s)
 	match res_parsing {
 		.ok {
 			res.u = converter(mut pn)
@@ -410,6 +420,13 @@ pub fn atof64(s string) !f64 {
 		.minf {
 			res.u = double_minus_infinity
 		}
+		.extra_char {
+			if param.allow_extra_chars {
+				res.u = converter(mut pn)
+			} else {
+				return error('extra char after number')
+			}
+		}
 		.invalid_number {
 			return error('not a number')
 		}
diff --git a/vlib/strconv/atof_test.c.v b/vlib/strconv/atof_test.c.v
index c40a41c421..61d9513ff2 100644
--- a/vlib/strconv/atof_test.c.v
+++ b/vlib/strconv/atof_test.c.v
@@ -20,6 +20,9 @@ fn test_atof() {
 		0.0,
 		-0.0,
 		31234567890123,
+		0.01,
+		2000,
+		-300,
 	]
 
 	// strings
@@ -31,6 +34,9 @@ fn test_atof() {
 		'0.0',
 		'-0.0',
 		'31234567890123',
+		'1e-2',
+		'+2e+3',
+		'-3.0e+2',
 	]
 
 	// check conversion case 1 string <=> string
@@ -89,4 +95,16 @@ fn test_atof_errors() {
 	} else {
 		assert err.str() == 'not a number'
 	}
+	if x := strconv.atof64('uu577.01') {
+		eprintln('> x: ${x}')
+		assert false // strconv.atof64 should have failed
+	} else {
+		assert err.str() == 'not a number'
+	}
+	if x := strconv.atof64('123.33xyz') {
+		eprintln('> x: ${x}')
+		assert false // strconv.atof64 should have failed
+	} else {
+		assert err.str() == 'extra char after number'
+	}
 }