diff -up src/sage/libs/ecl.pyx.orig src/sage/libs/ecl.pyx
--- src/sage/libs/ecl.pyx.orig	2020-07-07 09:07:43.622621879 -0600
+++ src/sage/libs/ecl.pyx	2020-07-09 10:04:16.260992211 -0600
@@ -15,7 +15,7 @@ Library interface to Embeddable Common L
 #adapted to work with pure Python types.
 
 from libc.stdlib cimport abort
-from libc.signal cimport SIGINT, SIGBUS, SIGSEGV
+from libc.signal cimport SIGINT, SIGBUS, SIGSEGV, SIGFPE
 from libc.signal cimport raise_ as signal_raise
 from posix.signal cimport sigaction, sigaction_t
 cimport cysignals.signals
@@ -47,9 +47,14 @@ cdef extern from "eclsig.h":
     void ecl_sig_off()
     cdef sigaction_t ecl_sigint_handler
     cdef sigaction_t ecl_sigbus_handler
+    cdef sigaction_t ecl_sigfpe_handler
     cdef sigaction_t ecl_sigsegv_handler
     cdef mpz_t ecl_mpz_from_bignum(cl_object obj)
     cdef cl_object ecl_bignum_from_mpz(mpz_t num)
+    cdef int fegetexcept()
+    cdef int feenableexcept(int)
+    cdef int fedisableexcept(int)
+    cdef int ecl_feflags
 
 cdef cl_object string_to_object(char * s):
     return ecl_read_from_cstring(s)
@@ -232,6 +237,7 @@ def init_ecl():
     global ecl_has_booted
     cdef char *argv[1]
     cdef sigaction_t sage_action[32]
+    cdef int sage_fpes
     cdef int i
 
     if ecl_has_booted:
@@ -248,6 +254,8 @@ def init_ecl():
     for i in range(1,32):
         sigaction(i, NULL, &sage_action[i])
 
+    sage_fpes = fegetexcept()
+
     #initialize ECL
     ecl_set_option(ECL_OPT_SIGNAL_HANDLING_THREAD, 0)
     cl_boot(1, argv)
@@ -255,12 +263,19 @@ def init_ecl():
     #save signal handler from ECL
     sigaction(SIGINT, NULL, &ecl_sigint_handler)
     sigaction(SIGBUS, NULL, &ecl_sigbus_handler)
+    sigaction(SIGFPE, NULL, &ecl_sigfpe_handler)
     sigaction(SIGSEGV, NULL, &ecl_sigsegv_handler)
 
+    #save ECL's floating point exception flags
+    ecl_feflags = fegetexcept()
+
     #and put the Sage signal handlers back
     for i in range(1,32):
         sigaction(i, &sage_action[i], NULL)
 
+    fedisableexcept(ecl_feflags)
+    feenableexcept(sage_fpes)
+
     #initialise list of objects and bind to global variable
     # *SAGE-LIST-OF-OBJECTS* to make it rooted in the reachable tree for the GC
     list_of_objects=cl_cons(Cnil,cl_cons(Cnil,Cnil))
diff -up src/sage/libs/eclsig.h.orig src/sage/libs/eclsig.h
--- src/sage/libs/eclsig.h.orig	2020-05-20 16:33:41.000000000 -0600
+++ src/sage/libs/eclsig.h	2020-07-09 10:01:25.618299374 -0600
@@ -9,25 +9,59 @@
 
 
 #include <signal.h>
+
+/* Rummage around to determine how ECL was configured */
+#define ECL_AVOID_FPE_H  /* Prevent some local includes */
+#include <ecl/config-internal.h>
+
+#ifdef HAVE_FENV_H
+#include <fenv.h>
+#ifndef FE_ALL_EXCEPT
+#define FE_ALL_EXCEPT FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW | FE_INVALID
+#endif
+#else
+#ifndef FE_ALL_EXCEPT
+#define FE_ALL_EXCEPT 0
+#endif
+#endif
+
+#ifndef HAVE_FEENABLEEXCEPT
+/* These are GNU extensions */
+#define fegetexcept() 0
+#define feenablexcept(flags)
+#define fdisableexcept(flags)
+#endif
+
 static struct sigaction ecl_sigint_handler;
 static struct sigaction ecl_sigbus_handler;
+static struct sigaction ecl_sigfpe_handler;
 static struct sigaction ecl_sigsegv_handler;
 static struct sigaction sage_sigint_handler;
 static struct sigaction sage_sigbus_handler;
+static struct sigaction sage_sigfpe_handler;
 static struct sigaction sage_sigsegv_handler;
+static int ecl_feflags;
+static int sage_feflags;
 
 static inline void set_ecl_signal_handler(void)
 {
     sigaction(SIGINT, &ecl_sigint_handler, &sage_sigint_handler);
     sigaction(SIGBUS, &ecl_sigbus_handler, &sage_sigbus_handler);
+    sigaction(SIGFPE, &ecl_sigfpe_handler, &sage_sigfpe_handler);
     sigaction(SIGSEGV, &ecl_sigsegv_handler, &sage_sigsegv_handler);
+    /* sage_feflags should be 0; we don't set them otherwise */
+    sage_feflags = fedisableexcept(FE_ALL_EXCEPT);
+    feenableexcept(ecl_feflags);
 }
 
 static inline void unset_ecl_signal_handler(void)
 {
     sigaction(SIGINT, &sage_sigint_handler, NULL);
     sigaction(SIGBUS, &sage_sigbus_handler, NULL);
+    sigaction(SIGFPE, &sage_sigfpe_handler, NULL);
     sigaction(SIGSEGV, &sage_sigsegv_handler, NULL);
+    ecl_feflags = fedisableexcept(FE_ALL_EXCEPT);
+    feenableexcept(sage_feflags);
 }
 
 /* This MUST be a macro because sig_on() must be in the same
diff -up src/sage/libs/mpmath/ext_impl.pyx.orig src/sage/libs/mpmath/ext_impl.pyx
--- src/sage/libs/mpmath/ext_impl.pyx.orig	2020-05-20 16:33:41.000000000 -0600
+++ src/sage/libs/mpmath/ext_impl.pyx	2020-07-09 10:01:25.620299371 -0600
@@ -162,9 +162,9 @@ opts_double_precision.rounding = ROUND_N
 opts_mini_prec.prec = 5
 opts_mini_prec.rounding = ROUND_D
 
-cdef double _double_inf = float("1e300") * float("1e300")
-cdef double _double_ninf = -_double_inf
-cdef double _double_nan = _double_inf - _double_inf
+cdef double _double_inf = float("inf")
+cdef double _double_ninf = float("-inf")
+cdef double _double_nan = float("nan")
 
 cdef inline void MPF_init(MPF *x):
     """Allocate space and set value to zero.