diff --git a/configure.ac b/configure.ac
index d1d47f8d..c43769ff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -169,6 +169,7 @@ return sizeof(x) / CHAR_BIT != 16U
 dnl Checks for functions and headers
 
 AC_CHECK_FUNC(clock_gettime, , [AC_CHECK_LIB(rt, clock_gettime)])
+AC_CHECK_FUNC(fegetenv, , [AC_CHECK_LIB(m, fegetenv)])
 
 AC_CHECK_FUNCS([SecureZeroMemory])
 
diff --git a/src/libsodium/crypto_onetimeauth/poly1305/53/auth_poly1305.c b/src/libsodium/crypto_onetimeauth/poly1305/53/auth_poly1305.c
index d7cf4982..1861abe6 100644
--- a/src/libsodium/crypto_onetimeauth/poly1305/53/auth_poly1305.c
+++ b/src/libsodium/crypto_onetimeauth/poly1305/53/auth_poly1305.c
@@ -10,6 +10,8 @@ Public domain.
 
 #include "crypto_onetimeauth.h"
 
+#pragma STDC FENV_ACCESS ON
+
 typedef uint8_t  uchar;
 typedef int32_t  int32;
 typedef uint32_t uint32;