diff --git a/config.tests/unix/clock-gettime/clock-gettime.cpp b/config.tests/unix/clock-gettime/clock-gettime.cpp
index 486cdc6b38f..cef9f6a1aeb 100644
--- a/config.tests/unix/clock-gettime/clock-gettime.cpp
+++ b/config.tests/unix/clock-gettime/clock-gettime.cpp
@@ -47,8 +47,6 @@ int main(int, char **)
     clock_gettime(CLOCK_REALTIME, &ts);
 #else
 #  error "Feature _POSIX_TIMERS not available"
-    // MIPSpro doesn't understand #error, so force a compiler error
-    force_compiler_error = true;
 #endif
     return 0;
 }
diff --git a/config.tests/unix/clock-monotonic/clock-monotonic.cpp b/config.tests/unix/clock-monotonic/clock-monotonic.cpp
index 0e75ed5a59e..777a6d1c213 100644
--- a/config.tests/unix/clock-monotonic/clock-monotonic.cpp
+++ b/config.tests/unix/clock-monotonic/clock-monotonic.cpp
@@ -47,8 +47,6 @@ int main(int, char **)
     clock_gettime(CLOCK_MONOTONIC, &ts);
 #else
 #  error "Feature _POSIX_MONOTONIC_CLOCK not available"
-    // MIPSpro doesn't understand #error, so force a compiler error
-    force_compiler_error = true;
 #endif
     return 0;
 }
diff --git a/config.tests/unix/getifaddrs/getifaddrs.cpp b/config.tests/unix/getifaddrs/getifaddrs.cpp
index ad1ecc3fb2a..a66ce4af37b 100644
--- a/config.tests/unix/getifaddrs/getifaddrs.cpp
+++ b/config.tests/unix/getifaddrs/getifaddrs.cpp
@@ -40,10 +40,6 @@
 /* Sample program for configure to test for if_nametoindex support
 on target platforms. */
 
-#if defined(__hpux)
-#define _HPUX_SOURCE
-#endif
-
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <net/if.h>
diff --git a/config.tests/unix/gnu-libiconv/gnu-libiconv.cpp b/config.tests/unix/gnu-libiconv/gnu-libiconv.cpp
index 1276311e080..fe4b87b9230 100644
--- a/config.tests/unix/gnu-libiconv/gnu-libiconv.cpp
+++ b/config.tests/unix/gnu-libiconv/gnu-libiconv.cpp
@@ -37,9 +37,6 @@
 **
 ****************************************************************************/
 
-#if defined(__sgi)
-#error "iconv not supported on IRIX"
-#else
 #include <iconv.h>
 
 int main(int, char **)
@@ -55,4 +52,3 @@ int main(int, char **)
 
     return 0;
 }
-#endif
diff --git a/config.tests/unix/iconv/iconv.cpp b/config.tests/unix/iconv/iconv.cpp
index 993a12c7ee7..be4236436f6 100644
--- a/config.tests/unix/iconv/iconv.cpp
+++ b/config.tests/unix/iconv/iconv.cpp
@@ -37,9 +37,6 @@
 **
 ****************************************************************************/
 
-#if defined(__sgi)
-#error "iconv not supported on IRIX"
-#else
 #include <iconv.h>
 
 int main(int, char **)
@@ -55,4 +52,3 @@ int main(int, char **)
 
     return 0;
 }
-#endif
diff --git a/config.tests/unix/ipv6ifname/ipv6ifname.cpp b/config.tests/unix/ipv6ifname/ipv6ifname.cpp
index bf2fe6f6ae2..fd58e85adb4 100644
--- a/config.tests/unix/ipv6ifname/ipv6ifname.cpp
+++ b/config.tests/unix/ipv6ifname/ipv6ifname.cpp
@@ -40,10 +40,6 @@
 /* Sample program for configure to test for if_nametoindex support
 on target platforms. */
 
-#if defined(__hpux)
-#define _HPUX_SOURCE
-#endif
-
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <net/if.h>