diff --git a/src/math/logb.c b/src/math/logb.c
index 624425a81165b219a973dee4c3d0f6cbe2c3c43c..7f8bdfae19f8ca0a85b611d38a73695ccf588e43 100644
--- a/src/math/logb.c
+++ b/src/math/logb.c
@@ -1,4 +1,4 @@
-#include "libm.h"
+#include <math.h>
 
 /*
 special cases:
@@ -12,6 +12,6 @@ double logb(double x)
 	if (!isfinite(x))
 		return x * x;
 	if (x == 0)
-		return -1/(x+0);
+		return -1/(x*x);
 	return ilogb(x);
 }
diff --git a/src/math/logbf.c b/src/math/logbf.c
index 950d35697bbe4abaa9a0ac83b70d5dbf6229359b..a0a0b5ed5be57de3e3ce05811af631f2ca88898a 100644
--- a/src/math/logbf.c
+++ b/src/math/logbf.c
@@ -1,10 +1,10 @@
-#include "libm.h"
+#include <math.h>
 
 float logbf(float x)
 {
 	if (!isfinite(x))
 		return x * x;
 	if (x == 0)
-		return -1/(x+0);
+		return -1/(x*x);
 	return ilogbf(x);
 }
diff --git a/src/math/logbl.c b/src/math/logbl.c
index f3850745812bcfdc797603502d188bf4245b9c10..962973a7b99bfffdcb2c1677a3c0b2ba5f87d357 100644
--- a/src/math/logbl.c
+++ b/src/math/logbl.c
@@ -1,4 +1,4 @@
-#include "libm.h"
+#include <math.h>
 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
 long double logbl(long double x)
 {
@@ -10,7 +10,7 @@ long double logbl(long double x)
 	if (!isfinite(x))
 		return x * x;
 	if (x == 0)
-		return -1/(x+0);
+		return -1/(x*x);
 	return ilogbl(x);
 }
 #endif