diff --git a/configure b/configure
index fb69ac87ef..23da910acb 100755
--- a/configure
+++ b/configure
@@ -3006,7 +3006,7 @@ if test "$_posix4" = yes ; then
 fi
 echores "$_posix4"
 
-for func in llrint log2 lrint lrintf round roundf truncf; do
+for func in exp2 exp2f llrint log2 log2f lrint lrintf round roundf truncf; do
 echocheck $func
 cat > $TMPC << EOF
 #include <math.h>
@@ -8682,12 +8682,15 @@ $def_winsock2_h
 
 
 /* system functions */
+$def_exp2
+$def_exp2f
 $def_gethostbyname2
 $def_gettimeofday
 $def_glob
 $def_langinfo
 $def_llrint
 $def_log2
+$def_log2f
 $def_lrint
 $def_lrintf
 $def_map_memalign