Index: src/svg/path-string.cpp
===================================================================
--- src/svg/path-string.cpp	(Revision 22416)
+++ src/svg/path-string.cpp	(Arbeitskopie)
@@ -125,12 +125,10 @@
 }
 
 void Inkscape::SVG::PathString::State::appendNumber(double v, int precision, int minexp) {
-    size_t const reserve = precision+1+1+1+1+3; // Just large enough to hold the maximum number of digits plus a sign, a period, the letter 'e', another sign and three digits for the exponent
-    size_t const oldsize = str.size();
-    str.append(reserve, (char)0);
-    char* begin_of_num = const_cast<char*>(str.data()+oldsize); // Slightly evil, I know (but std::string should be storing its data in one big block of memory, so...)
-    size_t added = sp_svg_number_write_de(begin_of_num, v, precision, minexp);
-    str.resize(oldsize+added); // remove any trailing characters
+    size_t const reserve = precision+1+1+1+1+1+3; // Just large enough to hold the maximum number of digits plus a dot, a sign, a period, the letter 'e', another sign and three digits for the exponent
+    char* float_buffer[reserve + 1];
+    size_t added = sp_svg_number_write_de(float_buffer, v, precision, minexp);
+    str.append(float_buffer, added); // remove any trailing characters
 }
 
 void Inkscape::SVG::PathString::State::appendNumber(double v, double &rv, int precision, int minexp) {