diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9ecad3a6e..fab9150ce 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -494,7 +494,7 @@ if(LIBC)
             strlen _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa
             _ultoa strtol strtoul strtoll strtod atoi atof strcmp strncmp
             _stricmp _strnicmp sscanf atan atan2 acos asin ceil copysign cos
-            cosf fabs floor log pow scalbn sin sinf sqrt)
+            cosf fabs floor log pow scalbn sin sinf sqrt sqrtf tan tanf)
       string(TOUPPER ${_FN} _UPPER)
       set(HAVE_${_UPPER} 1)
     endforeach()
@@ -541,7 +541,7 @@ if(LIBC)
       set(CMAKE_REQUIRED_LIBRARIES m)
       foreach(_FN
               atan atan2 ceil copysign cos cosf fabs floor log pow scalbn sin
-              sinf sqrt)
+              sinf sqrt sqrtf tan tanf)
         string(TOUPPER ${_FN} _UPPER)
         set(_HAVEVAR "HAVE_${_UPPER}")
         check_function_exists("${_FN}" ${_HAVEVAR})
diff --git a/configure b/configure
index 4ce116362..b8cada0a6 100755
--- a/configure
+++ b/configure
@@ -16639,7 +16639,7 @@ if test "x$ac_cv_lib_m_pow" = xyes; then :
   LIBS="$LIBS -lm"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"
 fi
 
-    for ac_func in atan atan2 acos asin ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt tan tanf
+    for ac_func in atan atan2 acos asin ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt sqrtf tan tanf
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.in b/configure.in
index 2604fa280..4f9909c26 100644
--- a/configure.in
+++ b/configure.in
@@ -271,7 +271,7 @@ if test x$enable_libc = xyes; then
     AC_CHECK_FUNCS(malloc calloc realloc free getenv setenv putenv unsetenv qsort abs bcopy memset memcpy memmove strlen strlcpy strlcat strdup _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp vsscanf vsnprintf fseeko fseeko64 sigaction setjmp nanosleep sysconf sysctlbyname)
 
     AC_CHECK_LIB(m, pow, [LIBS="$LIBS -lm"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"])
-    AC_CHECK_FUNCS(atan atan2 acos asin ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt tan tanf)
+    AC_CHECK_FUNCS(atan atan2 acos asin ceil copysign cos cosf fabs floor log pow scalbn sin sinf sqrt sqrtf tan tanf)
 
     AC_CHECK_LIB(iconv, iconv_open, [LIBS="$LIBS -liconv"; EXTRA_LDFLAGS="$EXTRA_LDFLAGS -liconv"])
     AC_CHECK_FUNCS(iconv)
diff --git a/src/libm/s_tan.c b/src/libm/s_tan.c
index 5a2bc930c..18c8f5b06 100644
--- a/src/libm/s_tan.c
+++ b/src/libm/s_tan.c
@@ -39,7 +39,7 @@
  *	TRIG(x) returns trig(x) nearly rounded
  */
 
-#include "math.h"
+#include "math_libm.h"
 #include "math_private.h"
 
 double tan(double x)