diff --git a/_lua5.1-tests/math.lua b/_lua5.1-tests/math.lua
index 21429a6f..f82ed6c1 100644
--- a/_lua5.1-tests/math.lua
+++ b/_lua5.1-tests/math.lua
@@ -52,6 +52,7 @@ assert(tonumber(string.rep('1', 32), 2) + 1 == 2^32)
 assert(tonumber('-fffffFFFFF', 16)-1 == -2^40)
 assert(tonumber('ffffFFFF', 16)+1 == 2^32)
 assert(tonumber('0xF') == 15)
+assert(tonumber('5e-07') == 0.0000005)
 
 assert(1.1 == 1.+.1)
 print(100.0, 1E2, .01)
diff --git a/baselib.go b/baselib.go
index aa2c08a9..f655aea1 100644
--- a/baselib.go
+++ b/baselib.go
@@ -410,7 +410,7 @@ func baseToNumber(L *LState) int {
 		L.Push(lv)
 	case LString:
 		str := strings.Trim(string(lv), " \n\t")
-		if strings.Index(str, ".") > -1 {
+		if strings.Contains(str, ".") || strings.Contains(str, "e-") {
 			if v, err := strconv.ParseFloat(str, LNumberBit); err != nil {
 				L.Push(LNil)
 			} else {