diff --git a/ZString.cpp b/ZString.cpp
index 9f45f5b..6387e08 100644
--- a/ZString.cpp
+++ b/ZString.cpp
@@ -1,4 +1,3 @@
-
 #include "ZString.h"
 #include "Log.h"
 #include "Exception.h"
@@ -125,7 +124,56 @@ namespace coreutils {
    }
 
    double ZString::asDouble() {
-      return strtod(cursor, &cursor);
+      double value = 0;
+      bool negative = false;
+      char *end = data + length;
+      if(*cursor == '-') {
+	 negative = true;
+	 ++cursor;
+      } else if(*cursor == '+') 
+	   ++cursor;
+      if(cursor == end)
+	return 0;
+      while((*cursor >= '0') && (*cursor <= '9')) {
+	 value *= 10;
+	 value += *cursor - 48;
+	 ++cursor;
+	 if(cursor == end) {
+	    if(negative)
+	      return -value;
+	    else
+	      return value;
+	 }	 
+      }
+      if(*cursor != '.') 
+	if(cursor == end) {
+	   if(negative)
+	     return -value;
+	   else
+	     return value;
+	}	       
+      ++cursor;
+      if(cursor == end) {
+	 if(negative)
+	   return -value;
+	 else
+	   return value;
+      }	 
+      double div = 10;
+      while((*cursor >= '0') && (*cursor <= '9')) {
+	 value += (*cursor - 48) / div;
+	 div *= 10;
+	 ++cursor;
+	 if(cursor == end) {
+	    if(negative)
+	      return -value;
+	    else
+	      return value;
+	 }	 
+      }             
+      if(negative)
+	return -value;
+      return value;
    }
 
    int ZString::incrementCursor(int length) {
diff --git a/testing/zstring_test.cpp b/testing/zstring_test.cpp
index 974af57..fe8cf6b 100644
--- a/testing/zstring_test.cpp
+++ b/testing/zstring_test.cpp
@@ -99,5 +99,8 @@ int main(int argc, char **argv) {
    std::cout << "[" << test18.find(".") << "] " << test18.parsed() << ":" << test18.unparsed() << std::endl;
    test18.reset();
    std::cout << "[" << test18.find("x") << "] " << test18.parsed() << ":" << test18.unparsed() << std::endl;
+
+   coreutils::ZString test19("-16473.65476Z");
+   std::cout << test19.asDouble() << ":" << test19.unparsed() << std::endl;
    
 }