diff --git a/man2/_exit.2 b/man2/_exit.2
index 072a1d225..c016eaab6 100644
--- a/man2/_exit.2
+++ b/man2/_exit.2
@@ -46,7 +46,8 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR _Exit ():
 .RS 4
-_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE;
+_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99
diff --git a/man3/abs.3 b/man3/abs.3
index 2f367608a..71ae15746 100644
--- a/man3/abs.3
+++ b/man3/abs.3
@@ -55,7 +55,8 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR llabs ():
 .RS 4
-_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE;
+_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99
diff --git a/man3/atoi.3 b/man3/atoi.3
index c47ed418a..fba8f064c 100644
--- a/man3/atoi.3
+++ b/man3/atoi.3
@@ -52,7 +52,8 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR atoll ():
 .RS 4
-_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE;
+_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99
diff --git a/man3/strtod.3 b/man3/strtod.3
index 810bc75f5..0208c31e7 100644
--- a/man3/strtod.3
+++ b/man3/strtod.3
@@ -61,7 +61,8 @@ Feature Test Macro Requirements for glibc (see
 .BR strtof (),
 .BR strtold ():
 .RS 4
-_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE;
+_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99
diff --git a/man3/strtol.3 b/man3/strtol.3
index 3bd5011a0..347c08259 100644
--- a/man3/strtol.3
+++ b/man3/strtol.3
@@ -47,7 +47,8 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR strtoll ():
 .RS 4
-XOPEN_SOURCE >= 600 || _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE;
+XOPEN_SOURCE >= 600 || _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99
diff --git a/man3/strtoul.3 b/man3/strtoul.3
index 8ef98bed7..69831cd66 100644
--- a/man3/strtoul.3
+++ b/man3/strtoul.3
@@ -50,7 +50,8 @@ Feature Test Macro Requirements for glibc (see
 .ad l
 .BR strtoull ():
 .RS 4
-XOPEN_SOURCE >= 600 || _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE;
+XOPEN_SOURCE >= 600 || _BSD_SOURCE || _SVID_SOURCE || _ISOC99_SOURCE ||
+_POSIX_C_SOURCE\ >=\ 200112L;
 .br
 or
 .I cc\ -std=c99