diff --git a/tests/test125cells.c b/tests/test125cells.c
index 41023aec16d1a3619d58caf8fbb01f08285f0661..33e945abf74a8f3075c2bc7536cbebc4fa372a12 100644
--- a/tests/test125cells.c
+++ b/tests/test125cells.c
@@ -759,7 +759,7 @@ int main(int argc, char *argv[]) {
 
     /* Dump if necessary */
     if (n == 0) {
-      sprintf(outputFileName, "swift_dopair_125_%s.dat",
+      sprintf(outputFileName, "swift_dopair_125_%.150s.dat",
               outputFileNameExtension);
       dump_particle_fields(outputFileName, main_cell, solution, 0);
     }
@@ -876,7 +876,7 @@ int main(int argc, char *argv[]) {
   /* Output timing */
   message("Brute force calculation took : %15lli ticks.", toc - tic);
 
-  sprintf(outputFileName, "brute_force_125_%s.dat", outputFileNameExtension);
+  sprintf(outputFileName, "brute_force_125_%.150s.dat", outputFileNameExtension);
   dump_particle_fields(outputFileName, main_cell, solution, 0);
 
   /* Clean things to make the sanitizer happy ... */
diff --git a/tests/test27cells.c b/tests/test27cells.c
index ccaaad8e8644ae72973c9b93eb0af44c77061113..ada1b782cfff3866bf26937391007947e9c9a175 100644
--- a/tests/test27cells.c
+++ b/tests/test27cells.c
@@ -546,7 +546,7 @@ int main(int argc, char *argv[]) {
 
     /* Dump if necessary */
     if (i % 50 == 0) {
-      sprintf(outputFileName, "swift_dopair_27_%s.dat",
+      sprintf(outputFileName, "swift_dopair_27_%.150s.dat",
               outputFileNameExtension);
       dump_particle_fields(outputFileName, main_cell, cells);
     }
@@ -589,7 +589,7 @@ int main(int argc, char *argv[]) {
   end_calculation(main_cell, &cosmo);
 
   /* Dump */
-  sprintf(outputFileName, "brute_force_27_%s.dat", outputFileNameExtension);
+  sprintf(outputFileName, "brute_force_27_%.150s.dat", outputFileNameExtension);
   dump_particle_fields(outputFileName, main_cell, cells);
 
   /* Output timing */
diff --git a/tests/testActivePair.c b/tests/testActivePair.c
index 4a70e341d0160193da595274f47e943c76390c15..9629f7c2d092b5cc6f5b38d5ba9ab9e0b669a825 100644
--- a/tests/testActivePair.c
+++ b/tests/testActivePair.c
@@ -578,8 +578,8 @@ int main(int argc, char *argv[]) {
   runner->e = &engine;
 
   /* Create output file names. */
-  sprintf(swiftOutputFileName, "swift_dopair_%s.dat", outputFileNameExtension);
-  sprintf(bruteForceOutputFileName, "brute_force_pair_%s.dat",
+  sprintf(swiftOutputFileName, "swift_dopair_%.150s.dat", outputFileNameExtension);
+  sprintf(bruteForceOutputFileName, "brute_force_pair_%.150s.dat",
           outputFileNameExtension);
 
   /* Delete files if they already exist. */
@@ -632,9 +632,9 @@ int main(int argc, char *argv[]) {
   finalise = &end_calculation_force;
 
   /* Create new output file names. */
-  sprintf(swiftOutputFileName, "swift_dopair2_force_%s.dat",
+  sprintf(swiftOutputFileName, "swift_dopair2_force_%.150s.dat",
           outputFileNameExtension);
-  sprintf(bruteForceOutputFileName, "brute_force_dopair2_%s.dat",
+  sprintf(bruteForceOutputFileName, "brute_force_dopair2_%.150s.dat",
           outputFileNameExtension);
 
   /* Delete files if they already exist. */
diff --git a/tests/testPeriodicBC.c b/tests/testPeriodicBC.c
index 3e4cb5d3816ad706cd5f083912da7f453a2a0e5a..ffaa3bda0ccb62cd44169e228086267d2399c31f 100644
--- a/tests/testPeriodicBC.c
+++ b/tests/testPeriodicBC.c
@@ -512,9 +512,9 @@ int main(int argc, char *argv[]) {
   }
 
   /* Create output file names. */
-  sprintf(swiftOutputFileName, "swift_periodic_BC_%s.dat",
+  sprintf(swiftOutputFileName, "swift_periodic_BC_%.150s.dat",
           outputFileNameExtension);
-  sprintf(bruteForceOutputFileName, "brute_force_periodic_BC_%s.dat",
+  sprintf(bruteForceOutputFileName, "brute_force_periodic_BC_%.150s.dat",
           outputFileNameExtension);
 
   /* Delete files if they already exist. */