diff --git a/lib/msun/bsdsrc/b_log.c b/lib/msun/bsdsrc/b_log.c
index 95d366de6de5..b9f1473e0c8b 100644
--- a/lib/msun/bsdsrc/b_log.c
+++ b/lib/msun/bsdsrc/b_log.c
@@ -77,9 +77,6 @@ __FBSDID("$FreeBSD$");
  *	+Inf	return +Inf
 */
 
-#define endian		(((*(int *) &one)) ? 1 : 0)
-#define TRUNC(x)	*(((int *) &x) + endian) &= 0xf8000000
-
 #define N 128
 
 /* Table of log(Fj) = logF_head[j] + logF_tail[j], for Fj = 1+j/128.
@@ -438,7 +435,7 @@ __log__D(x) double x;
 #endif
 {
 	int m, j;
-	double F, f, g, q, u, v, u2, one = 1.0;
+	double F, f, g, q, u, v, u2;
 	volatile double u1;
 	struct Double r;
 
diff --git a/lib/msun/bsdsrc/b_tgamma.c b/lib/msun/bsdsrc/b_tgamma.c
index babf3261de89..a8e575539ab4 100644
--- a/lib/msun/bsdsrc/b_tgamma.c
+++ b/lib/msun/bsdsrc/b_tgamma.c
@@ -123,20 +123,12 @@ static struct Double ratfun_gam(double, double);
 #define Pa7	-1.44705562421428915453880392761e-02
 
 static const double zero = 0., one = 1.0, tiny = 1e-300;
-static int endian;
-
-/*
- * TRUNC sets trailing bits in a floating-point number to zero.
- * is a temporary variable.
- */
-#define TRUNC(x)	*(((int *) &x) + endian) &= 0xf8000000
 
 double
 tgamma(x)
 	double x;
 {
 	struct Double u;
-	endian = (*(int *) &one) ? 1 : 0;
 
 	if (x >= 6) {
 		if(x > 171.63)
diff --git a/lib/msun/bsdsrc/mathimpl.h b/lib/msun/bsdsrc/mathimpl.h
index 275b6247f3ee..5c22e7d3eb41 100644
--- a/lib/msun/bsdsrc/mathimpl.h
+++ b/lib/msun/bsdsrc/mathimpl.h
@@ -34,9 +34,32 @@
  * $FreeBSD$
  */
 
+#ifndef _MATHIMPL_H_
+#define	_MATHIMPL_H_
+
 #include <sys/cdefs.h>
 #include <math.h>
 
+#include "../src/math_private.h"
+
+/*
+ * TRUNC() is a macro that sets the trailing 27 bits in the mantissa of an
+ * IEEE double variable to zero.  It must be expression-like for syntactic
+ * reasons, and we implement this expression using an inline function
+ * instead of a pure macro to avoid depending on the gcc feature of
+ * statement-expressions.
+ */
+#define	TRUNC(d)	(_b_trunc(&(d)))
+
+static __inline void
+_b_trunc(volatile double *_dp)
+{
+	uint32_t _lw;
+
+	GET_LOW_WORD(_lw, *_dp);
+	SET_LOW_WORD(*_dp, _lw & 0xf8000000);
+}
+
 /*
  * Functions internal to the math package, yet not static.
  */
@@ -45,3 +68,5 @@ extern double	__exp__E();
 struct Double {double a, b;};
 double __exp__D(double, double);
 struct Double __log__D(double);
+
+#endif /* !_MATHIMPL_H_ */