diff --git a/src/types/decimal/decimal.cc b/src/types/decimal/decimal.cc
index b3c8060..b649be0 100644
--- a/src/types/decimal/decimal.cc
+++ b/src/types/decimal/decimal.cc
@@ -31,12 +31,20 @@ namespace types {
 Decimal::Decimal(const std::string & var) {
   try {
     int i = 0;
+    bool followingE = false;
+
     for (; i < var.length(); i++) {
-      if (var[i] != '.' && var[i] != 'e' && var[i] != 'E'
+      if (var[i] == 'e' || var[i] == 'E') {
+        followingE = true;
+      }
+      if ((var[i] == '-' || var[i] == '+') && i != 0 && !followingE) {
+        followingE = false;
+        break;
+      } else if (var[i] != '.' && var[i] != 'e' && var[i] != 'E'
         && var[i] != '-' && var[i] != '+'
         && (var[i] < 0x30 || var[i] > 0x39)) {
         break;
-        }
+      }
     }
 
     if (i == 0) {
diff --git a/src/types/decimal/decimal_p.h b/src/types/decimal/decimal_p.h
index 9e6e935..d0eee1b 100644
--- a/src/types/decimal/decimal_p.h
+++ b/src/types/decimal/decimal_p.h
@@ -88,7 +88,7 @@ class DecimalP {
   }
 
   DecimalP operator-() const {
-    return -(*m_ptr);
+    return Decimal("0") - (*m_ptr);
   }
 
   bool operator==(const DecimalP &v) const {