diff --git a/src/libnptm/Configuration.cpp b/src/libnptm/Configuration.cpp
index 7511a921aea3327c5a0b9bdb2c3d5a093f66f1b1..5d1c05d898179cca789efc59061ee3600a8a899c 100644
--- a/src/libnptm/Configuration.cpp
+++ b/src/libnptm/Configuration.cpp
@@ -1007,7 +1007,7 @@ void ScattererConfiguration::write_formatted(string file_name) {
 	for (int jxi476 = 0; jxi476 < number_of_scales; jxi476++) {
 	  double dc0_real = dc0_matrix[ic477 - 1][i478 - 1][jxi476].real();
 	  double dc0_img = dc0_matrix[ic477 - 1][i478 - 1][jxi476].imag();
-	  fprintf(output, "%5d%12.4lE%12.4lE\n", (jxi476 + 1), dc0_real, dc0_img);
+	  fprintf(output, "%5d %12.4lE%12.4lE\n", (jxi476 + 1), dc0_real, dc0_img);
 	}
       }
     }