diff --git a/science/FreeSOLID/Portfile b/science/FreeSOLID/Portfile
index a46a4f71bdd..2eb7a2da90c 100644
--- a/science/FreeSOLID/Portfile
+++ b/science/FreeSOLID/Portfile
@@ -7,7 +7,6 @@ version             2.1.2
 revision            3
 
 categories          science
-platforms           darwin
 license             LGPL-2
 maintainers         nomaintainer
 
@@ -17,7 +16,7 @@ long_description    FreeSOLID is a library for collision detection of three-dime
                     to be used in interactive 3D graphics applications.
 
 homepage            https://sourceforge.net/projects/freesolid/
-master_sites        sourceforge:freesolid
+master_sites        sourceforge:project/freesolid
 
 checksums           rmd160  0f7134913dc5a74d7a8508f43d98e5d4006b3603 \
                     sha256  89edc6afdd9d60c8020b2b865b61558c86a8928dc6f1773b9f4708b5c28eb873
@@ -26,6 +25,17 @@ use_zip             yes
 
 depends_lib         port:qhull
 
+# Update config.guess and config.sub to be able to build on arm64.
+depends_build-append    port:automake
+post-patch {
+    set automake_dirs [glob -directory ${prefix}/share automake-*]
+    set automake_dir [lindex [lsort -command vercmp $automake_dirs] end]
+    copy -force ${automake_dir}/config.guess ${automake_dir}/config.sub \
+        ${worksrcpath}
+}
+
+patchfiles          configure.patch
+
 post-extract {
     system "chmod +x ${worksrcpath}/configure"
 }
diff --git a/science/FreeSOLID/files/configure.patch b/science/FreeSOLID/files/configure.patch
new file mode 100644
index 00000000000..cd1ee4dfb1d
--- /dev/null
+++ b/science/FreeSOLID/files/configure.patch
@@ -0,0 +1,40 @@
+Fix implicit declaration errors.
+
+--- configure.orig	2015-04-24 13:54:36
++++ configure	2025-09-11 11:43:14
+@@ -5065,14 +5065,14 @@
+ 
+ #define XOR(e, f) (((e) && !(f)) || (!(e) && (f)))
+ int
+-main ()
++main (void)
+ {
+   int i;
+   for (i = 0; i < 256; i++)
+     if (XOR (islower (i), ISLOWER (i))
+ 	|| toupper (i) != TOUPPER (i))
+-      exit(2);
+-  exit (0);
++      return (2);
++  return (0);
+ }
+ _ACEOF
+ rm -f conftest$ac_exeext
+@@ -19498,14 +19498,14 @@
+ 
+ #define XOR(e, f) (((e) && !(f)) || (!(e) && (f)))
+ int
+-main ()
++main (void)
+ {
+   int i;
+   for (i = 0; i < 256; i++)
+     if (XOR (islower (i), ISLOWER (i))
+ 	|| toupper (i) != TOUPPER (i))
+-      exit(2);
+-  exit (0);
++      return (2);
++  return (0);
+ }
+ _ACEOF
+ rm -f conftest$ac_exeext