diff --git a/ChangeLog b/ChangeLog
index b99032e..238ca86 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2005-08-27  Bruno Haible  <bruno@clisp.org>
+
+	Make the long-float overflow check work on 64-bit platforms.
+	* src/float/lfloat/cl_LF.h (LF_exp_mid, LF_exp_high): Define as
+	'unsigned int', not 'unsigned long'.
+
 2005-08-27  Bruno Haible  <bruno@clisp.org>
 
 	* modules.h (CL_OUTPUT_LABEL): Work around redundant duplication
diff --git a/src/float/lfloat/cl_LF.h b/src/float/lfloat/cl_LF.h
index 3a3fc96..8da8d40 100644
--- a/src/float/lfloat/cl_LF.h
+++ b/src/float/lfloat/cl_LF.h
@@ -20,9 +20,11 @@ struct cl_heap_lfloat : cl_heap {
 // so that a LF has not fewer mantissa bits than a DF.
   #define LF_minlen  ceiling(53,intDsize)
 // Exponent.
+// Define as 'unsigned int', not 'unsigned long', so that
+// LF_exp_high+1 wraps around to 0 just like the 'expo' field does.
   #define LF_exp_low  1
-  #define LF_exp_mid  0x80000000UL
-  #define LF_exp_high 0xFFFFFFFFUL
+  #define LF_exp_mid  0x80000000U
+  #define LF_exp_high 0xFFFFFFFFU
 
 inline cl_heap_lfloat* TheLfloat (cl_heap_lfloat* p)
 	{ return p; }