diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h
index 2ab5f03a662..a441b5457b2 100644
--- a/src/gallium/auxiliary/util/u_math.h
+++ b/src/gallium/auxiliary/util/u_math.h
@@ -605,8 +605,9 @@ util_memcpy_cpu_to_le32(void * restrict dest, const void * restrict src, size_t
 /**
  * Clamp X to [MIN, MAX].
  * This is a macro to allow float, int, uint, etc. types.
+ * We arbitrarily turn NaN into MIN.
  */
-#define CLAMP( X, MIN, MAX )  ( (X)<(MIN) ? (MIN) : ((X)>(MAX) ? (MAX) : (X)) )
+#define CLAMP( X, MIN, MAX )  ( (X)>(MIN) ? ((X)>(MAX) ? (MAX) : (X)) : (MIN) )
 
 #define MIN2( A, B )   ( (A)<(B) ? (A) : (B) )
 #define MAX2( A, B )   ( (A)>(B) ? (A) : (B) )
diff --git a/src/util/macros.h b/src/util/macros.h
index a10f1de8145..a66f1bfed07 100644
--- a/src/util/macros.h
+++ b/src/util/macros.h
@@ -244,8 +244,8 @@ do {                       \
 /** Compute ceiling of integer quotient of A divided by B. */
 #define DIV_ROUND_UP( A, B )  ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 )
 
-/** Clamp X to [MIN,MAX] */
-#define CLAMP( X, MIN, MAX )  ( (X)<(MIN) ? (MIN) : ((X)>(MAX) ? (MAX) : (X)) )
+/** Clamp X to [MIN,MAX].  Turn NaN into MIN, arbitrarily. */
+#define CLAMP( X, MIN, MAX )  ( (X)>(MIN) ? ((X)>(MAX) ? (MAX) : (X)) : (MIN) )
 
 /** Minimum of two values: */
 #define MIN2( A, B )   ( (A)<(B) ? (A) : (B) )