diff --git a/DDCore/include/DD4hep/Handle.h b/DDCore/include/DD4hep/Handle.h
index 22917aa921333392b6a85c8a2203eb8b6e83653b..a82299f91397c5ebc73966886facab6b6d0852ee 100644
--- a/DDCore/include/DD4hep/Handle.h
+++ b/DDCore/include/DD4hep/Handle.h
@@ -51,9 +51,9 @@ namespace DD4hep {
     /// String conversions: integer value to string  \ingroup DD4HEP_GEOMETRY
     std::string _toString(int value, const char* fmt = "%d");
     /// String conversions: float value to string  \ingroup DD4HEP_GEOMETRY
-    std::string _toString(float value, const char* fmt = "%f");
+    std::string _toString(float value, const char* fmt = "%30.30f");
     /// String conversions: double value to string  \ingroup DD4HEP_GEOMETRY
-    std::string _toString(double value, const char* fmt = "%f");
+    std::string _toString(double value, const char* fmt = "%30.30f");
     /// Pointer to text conversion
     std::string _ptrToString(const void* p, const char* fmt = "%p");
     /// Format any pointer (64 bits) to string  \ingroup DD4HEP_XML
diff --git a/DDCore/include/XML/XMLElements.h b/DDCore/include/XML/XMLElements.h
index 1f93556d0dae172e841998b169baf144f8f86106..e9f38bf15e7cc2fca59e96a91a4d554ef27d6ec3 100644
--- a/DDCore/include/XML/XMLElements.h
+++ b/DDCore/include/XML/XMLElements.h
@@ -106,9 +106,9 @@ namespace DD4hep {
     /// Format signed long integer to string with atrbitrary format  \ingroup DD4HEP_XML
     std::string _toString(long i, const char* fmt = "%fd");
     /// Format single procision float number (32 bits) to string with atrbitrary format  \ingroup DD4HEP_XML
-    std::string _toString(float d, const char* fmt = "%f");
+    std::string _toString(float d, const char* fmt = "%30.30f");
     /// Format double procision float number (64 bits) to string with atrbitrary format  \ingroup DD4HEP_XML
-    std::string _toString(double d, const char* fmt = "%f");
+    std::string _toString(double d, const char* fmt = "%30.30f");
     /// Format void pointer (64 bits) to string with atrbitrary format  \ingroup DD4HEP_XML
     std::string _ptrToString(const void* p, const char* fmt = "%p");
     /// Format void pointer (64 bits) to string with atrbitrary format  \ingroup DD4HEP_XML