diff --git a/agent-ini/src/IniParser.cc b/agent-ini/src/IniParser.cc
index e68f091ad..6ea002f09 100644
--- a/agent-ini/src/IniParser.cc
+++ b/agent-ini/src/IniParser.cc
@@ -22,6 +22,8 @@
 #include <sys/types.h>
 #include <glob.h>
 #include <cassert>
+#include <cstdarg>
+#include <stdexcept>
 
 #include "IniParser.h"
 #include "IniFile.h"
@@ -1015,9 +1017,33 @@ int IniParser::write()
     inifile.clean ();
     return bugs ? -1 : 0;
 }
+
+/** sprintf to a std::string, throwing runtime_error on OOM */
+std::string format (const char * format, ...) {
+    // copied from y2util/stringutil.h but added the throw
+    // since we don't want to silently corrupt config files
+    char * buf = 0;
+    std::string val;
+
+    va_list ap;
+    va_start( ap, format );
+
+    int numprinted = vasprintf(&buf, format, ap);
+    if (numprinted >= 0) {
+        val = buf;
+        free( buf );
+    }
+    else {
+        throw std::runtime_error("vasprintf failed in ag_ini. Out of memory?");
+    }
+
+    va_end( ap );
+    return val;
+}
+
 int IniParser::write_helper(IniSection&ini, ofstream&of, int depth)
 {
-    char * out_buffer;
+    string out_buffer;
     string indent;
     string indent2;
     int readby = ini.getReadBy ();
@@ -1033,9 +1059,8 @@ int IniParser::write_helper(IniSection&ini, ofstream&of, int depth)
         of << ini.getComment();
     if (readby>=0 && readby < (int)sections.size ())
 	{
-	    asprintf (&out_buffer, sections[readby].begin.out.c_str (), ini.getName());
+            out_buffer = format (sections[readby].begin.out.c_str (), ini.getName());
 	    of << indent << out_buffer << "\n";
-	    free (out_buffer);
 	}
     
     IniIterator
@@ -1056,9 +1081,8 @@ int IniParser::write_helper(IniSection&ini, ofstream&of, int depth)
 			of << e.getComment();
 		    if (e.getReadBy()>=0 && e.getReadBy() < (int)params.size ()) {
 			// bnc#492859, a fixed buffer is too small
-			asprintf (&out_buffer, params[e.getReadBy ()].line.out.c_str (), e.getName(), e.getValue());
+			out_buffer = format (params[e.getReadBy ()].line.out.c_str (), e.getName(), e.getValue());
 			of << indent2 << out_buffer << "\n";
-			free(out_buffer);
 		    }
 		    e.clean();
 		}
@@ -1068,9 +1092,8 @@ int IniParser::write_helper(IniSection&ini, ofstream&of, int depth)
         of << indent << ini.getEndComment();
     if (readby>=0 && readby < (int) sections.size () && sections[readby].end_valid)
 	{
-	    asprintf (&out_buffer, sections[readby].end.out.c_str (), ini.getName());
+	    out_buffer = format (sections[readby].end.out.c_str (), ini.getName());
 	    of << indent << out_buffer << "\n";
-	    free(out_buffer);
 	}
     ini.clean();
     return 0;
diff --git a/package/yast2-core.changes b/package/yast2-core.changes
index eb813fee3..5db077154 100644
--- a/package/yast2-core.changes
+++ b/package/yast2-core.changes
@@ -3,6 +3,7 @@ Wed May 23 15:35:00 CEST 2012 - mvidner@suse.cz
 
 - agent-ini: do not truncate strings longer than 2048
   while writing (bnc#492859, bnc#763386)
+- agent-ini: if we cannot format a string, fail loudly (bnc#763386#c10)
 - 2.17.35.4
 
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