diff --git a/lbtt/ChangeLog b/lbtt/ChangeLog
index c251d9955..6bbd41392 100644
--- a/lbtt/ChangeLog
+++ b/lbtt/ChangeLog
@@ -1,3 +1,14 @@
+2009-11-26  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Fix generation of random formulae on 64bits systems.
+
+	* src/main.cc (testLoop): Generate random short ints between 0 and
+	SHRT_MAX, not between 0 and LONG_MAX.  On systems where long ints
+	are 64bits, LRAND(0,LONG_MAX) was returning a value with the lower
+	32 bits set to 0, and the latter truncation to short int always
+	yielded the value 0.  Consequently all generated formulae were
+	identical...
+
 2009-11-25  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	* src/Configuration.cc (registerAlgorithm): Do not complain about
diff --git a/lbtt/src/main.cc b/lbtt/src/main.cc
index 622503f50..beb71052d 100644
--- a/lbtt/src/main.cc
+++ b/lbtt/src/main.cc
@@ -325,11 +325,11 @@ bool testLoop()
 
   SRAND(configuration.global_options.statespace_random_seed);
   for (int i = 0; i < 3; i++)
-    statespace_random_state[i] = static_cast<short int>(LRAND(0, LONG_MAX));
+    statespace_random_state[i] = static_cast<short int>(LRAND(0, SHRT_MAX));
 
   SRAND(configuration.global_options.formula_random_seed);
   for (int i = 0; i < 3; i++)
-    formula_random_state[i] = static_cast<short int>(LRAND(0, LONG_MAX));
+    formula_random_state[i] = static_cast<short int>(LRAND(0, SHRT_MAX));
 #endif /* HAVE_RAND48 */
 
   /*
@@ -367,7 +367,7 @@ bool testLoop()
     round_info.error = false;
     round_info.skip
       = (round_info.current_round < round_info.next_round_to_run);
-	
+
     if (!round_info.skip)
       printText(string("Round ") + toString(round_info.current_round)
 		+ " of " + toString(global_options.number_of_rounds) + "\n\n",
@@ -390,13 +390,13 @@ bool testLoop()
 	seed48(statespace_random_state);
 	for (int i = 0; i < 3; i++)
 	  statespace_random_state[i] = static_cast<short int>
-	                                 (LRAND(0, LONG_MAX));
+	                                 (LRAND(0, SHRT_MAX));
 #else
 	SRAND(global_options.statespace_random_seed);
 	configuration.global_options.statespace_random_seed
 	  = LRAND(0, RAND_MAX);
 #endif /* HAVE_RAND48 */
-	
+
 	if (global_options.statespace_change_interval == 0)
 	  round_info.next_round_to_change_statespace
 	    = global_options.number_of_rounds + 1;
@@ -434,7 +434,7 @@ bool testLoop()
        */
 
       round_info.fresh_formula
-	= (round_info.next_round_to_change_formula 
+	= (round_info.next_round_to_change_formula
 	     == round_info.current_round);
 
       if (round_info.fresh_formula)
@@ -442,7 +442,7 @@ bool testLoop()
 #ifdef HAVE_RAND48
 	seed48(formula_random_state);
 	for (int i = 0; i < 3; i++)
-	  formula_random_state[i] = static_cast<short int>(LRAND(0, LONG_MAX));
+	  formula_random_state[i] = static_cast<short int>(LRAND(0, SHRT_MAX));
 #else
 	SRAND(global_options.formula_random_seed);
 	configuration.global_options.formula_random_seed = LRAND(0, RAND_MAX);
@@ -743,7 +743,7 @@ bool testLoop()
 
 int main(int argc, char* argv[])
 {
-  try 
+  try
   {
     configuration.read(argc, argv);
   }
@@ -792,7 +792,7 @@ int main(int argc, char* argv[])
   using_history();
 #endif  /* HAVE_READLINE */
 
-  try 
+  try
   {
     allocateTempFilenames();
     if (!testLoop())