diff --git a/libexec/trick/configuration_processor b/libexec/trick/configuration_processor
index 3fada80e..b92f3664 100755
--- a/libexec/trick/configuration_processor
+++ b/libexec/trick/configuration_processor
@@ -16,9 +16,13 @@ use gte ;
 use s_source ;
 use trick_print ;
 use trick_version ;
+use get_paths ;
+use verbose_build ;
 
 my %sim ;
 my $cwd = cwd();
+my $verbose_build = verbose_build() ;
+my @ext_lib_paths = get_paths( "TRICK_EXT_LIB_DIRS" ) ;
 
 # override the print format for help message
 *Pod::Text::seq_i = sub { return "" . $_[1] . "" } ;
@@ -91,6 +95,10 @@ open LIBDEP, ">build/S_define.lib_deps" ;
 foreach my $file ( @{$sim{mis_entry_files}} ) {
     if ( $file ne "" ) {
         $file = abs_path(dirname($file)) . "/" . basename($file) ;
+        if ( my $path = get_containing_path( $file, @ext_lib_paths ) ) {
+            print "Dep Skip   TRICK_EXT_LIB_DIRS: $path" . substr($file, length $path) . "\n" if $verbose_build ;
+            next ;
+        }
         print LIBDEP "$file\n" ;
     }
 }
diff --git a/libexec/trick/make_makefile_src b/libexec/trick/make_makefile_src
index 5f16a0a2..3db90eec 100755
--- a/libexec/trick/make_makefile_src
+++ b/libexec/trick/make_makefile_src
@@ -14,6 +14,7 @@ use verbose_build ;
 my %processed_files ;
 my %non_lib_processed_files ;
 my $any_deps_changed = 0 ;
+my $verbose_build = verbose_build() ;
 
 sub exist_lib_deps(@) {
     my (@files_to_process) = @_ ;
@@ -24,8 +25,8 @@ sub exist_lib_deps(@) {
         my ( $file, $dir, $suffix) = fileparse($l, qr/\.[^.]*/) ;
         my ($lib_dep_file_name) = "build$dir${file}${suffix}.lib_deps" ;
         if ( ! -e $lib_dep_file_name ) {
-            $any_deps_changed =1 ;
-            print "NewDep     $l\n" ;
+            $any_deps_changed = 1 ;
+            print "New Dep    $l\n" ;
             return 1 ;
         }
     }
@@ -58,7 +59,7 @@ sub read_lib_deps($@) {
                     read_lib_deps($indent + 1 , @resolved_files) ;
                 }
             }
-        } elsif ( verbose_build() ) {
+        } elsif ( $verbose_build ) {
             print "Skipping   Previously processed file \"$l\"\n" ;
         }
     }
@@ -125,21 +126,6 @@ my @all_read_only_libs ;
 my @all_compile_libs ;
 my %files_by_dir ;
 
-my @exclude_dirs ;
-@exclude_dirs = split /:/ , "$ENV{TRICK_EXCLUDE}:$ENV{TRICK_EXT_LIB_DIRS}";
-# See if there are any elements in the exclude_dirs array
-if (scalar @exclude_dirs) {
-    @exclude_dirs = sort(@exclude_dirs );
-    # Error check - delete any element that is null
-    # (note: sort forced all blank names to front of array
-    @exclude_dirs = map { s/(^\s+|\s+$)//g ; $_ } @exclude_dirs ;
-    while ( scalar @exclude_dirs and not length @exclude_dirs[0] ) {
-        # Delete an element from the left side of an array (element zero)
-        shift @exclude_dirs ;
-    }
-    @exclude_dirs = map { (-e $_) ? abs_path($_) : $_ } @exclude_dirs ;
-}
-
 @all_cfly_files = keys %processed_files ;
 @all_read_only_libs = sort (grep /^-/ , @all_cfly_files) ;
 @all_compile_libs = grep /\.a$/ , @all_cfly_files ;
@@ -183,17 +169,6 @@ foreach my $directory ( keys %files_by_dir ) {
     }
 }
 
-foreach $k ( sort keys %files_by_dir ) {
-    foreach my $ie ( @exclude_dirs ) {
-        # if file location begins with $ie (an exclude dir)
-        if ( $k =~ /^\Q$ie/ ) {
-            delete $files_by_dir{$k} ;
-            print "excluding $k from build\n" ;
-            last ;  # break out of loop
-        }
-    }
-}
-
 my $wd = abs_path(cwd()) ;
 my $dt = localtime();
 my ($trick_ver) = get_trick_version() ;
diff --git a/libexec/trick/pm/get_lib_deps.pm b/libexec/trick/pm/get_lib_deps.pm
index 614bf326..90937e15 100644
--- a/libexec/trick/pm/get_lib_deps.pm
+++ b/libexec/trick/pm/get_lib_deps.pm
@@ -6,11 +6,15 @@ use File::Path qw(make_path) ;
 use Exporter ();
 use gte ;
 use get_paths ;
+use verbose_build ;
 @ISA = qw(Exporter);
 @EXPORT = qw(get_lib_deps write_lib_deps);
 
 use strict ;
 
+my $verbose_build = verbose_build() ;
+my @ext_lib_paths = get_paths( "TRICK_EXT_LIB_DIRS" ) ;
+
 sub get_lib_deps ($$) {
     my ($contents, $source_file_name) = @_ ;
     my ($lib_deps) ;
@@ -153,7 +157,16 @@ sub get_lib_deps ($$) {
             }
         }
     }
-    return (grep { !is_path_in($_, "TRICK_EXT_LIB_DIRS") } @ordered_resolved_files) ;
+
+    my @included_ordered_resolved_files;
+    foreach (@ordered_resolved_files) {
+        if ( my $exclude_path = get_containing_path( $_, @ext_lib_paths ) ) {
+            print "Dep Skip   TRICK_EXT_LIB_DIRS: $exclude_path" . substr($_, length $exclude_path) . "\n" if $verbose_build ;
+            next ;
+        }
+        push @included_ordered_resolved_files, $_ ;
+    }
+    return @included_ordered_resolved_files ;
 }
 
 sub write_lib_deps($) {
diff --git a/libexec/trick/pm/get_paths.pm b/libexec/trick/pm/get_paths.pm
index c44d25f1..675cb608 100644
--- a/libexec/trick/pm/get_paths.pm
+++ b/libexec/trick/pm/get_paths.pm
@@ -3,7 +3,7 @@ package get_paths ;
 use Exporter ();
 use Cwd 'abs_path' ;
 @ISA = qw(Exporter);
-@EXPORT = qw(get_paths get_include_paths get_defines is_path_in);
+@EXPORT = qw(get_paths get_include_paths get_defines get_containing_path);
 
 use strict ;
 
@@ -20,10 +20,11 @@ sub get_defines {
     return "$ENV{TRICK_CFLAGS} $ENV{TRICK_CXXFLAGS}" =~ /-D\S+/g
 }
 
-sub is_path_in {
-    foreach my $path (get_paths($_[1])) {
-        if ( $_[0] =~ /^\Q$path\E(.*)/ or abs_path($_[0]) =~ /^\Q$path\E(.*)/ ) {
-            return 1 ;
+sub get_containing_path {
+    my $path = shift;
+    foreach my $exclude_path (@_) {
+        if ( $path =~ /^\Q$exclude_path\E(.*)/ or abs_path($path) =~ /^\Q$exclude_path\E(.*)/ ) {
+            return $exclude_path ;
         }
     }
     return 0 ;
diff --git a/test/SIM_exclusion_mechanisms/RUN_test/input.py b/test/SIM_exclusion_mechanisms/RUN_test/input.py
new file mode 100644
index 00000000..e69de29b
diff --git a/test/SIM_exclusion_mechanisms/S_define b/test/SIM_exclusion_mechanisms/S_define
new file mode 100644
index 00000000..a03b3fc0
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/S_define
@@ -0,0 +1,26 @@
+// @trick_link_dependency{ExtLibDir.cpp}
+// @trick_link_dependency{ext_lib_dir/ExtLibDir.cpp}
+
+#include "sim_objects/default_trick_sys.sm"
+
+##include "Foo.hh"
+
+##include "Exclude.hh"
+##include "exclude/Exclude.hh"
+##include "symlinks/exclude_link_path/links/exclude/Exclude.hh"
+##include "symlinks/exclude_real_path/links/exclude/Exclude.hh"
+
+##include "IcgExclude.hh"
+##include "icg_exclude/IcgExclude.hh"
+##include "symlinks/exclude_link_path/links/icg_exclude/IcgExclude.hh"
+##include "symlinks/exclude_real_path/links/icg_exclude/IcgExclude.hh"
+
+##include "SwigExclude.hh"
+##include "swig_exclude/SwigExclude.hh"
+##include "symlinks/exclude_link_path/links/swig_exclude/SwigExclude.hh"
+##include "symlinks/exclude_real_path/links/swig_exclude/SwigExclude.hh"
+
+##include "ExtLibDir.hh"
+##include "ext_lib_dir/ExtLibDir.hh"
+##include "symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh"
+##include "symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh"
diff --git a/test/SIM_exclusion_mechanisms/S_overrides.mk b/test/SIM_exclusion_mechanisms/S_overrides.mk
new file mode 100644
index 00000000..a5c60c6d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/S_overrides.mk
@@ -0,0 +1,32 @@
+MODELS := $(CURDIR)/models
+TRICK_CXXFLAGS += -I$(MODELS)
+
+TRICK_EXCLUDE += :$(MODELS)/Exclude.hh
+TRICK_EXCLUDE += :$(MODELS)/exclude
+TRICK_EXCLUDE += :$(MODELS)/symlinks/exclude_link_path/links/exclude
+TRICK_EXCLUDE += :$(MODELS)/symlinks/exclude_real_path/real/exclude
+
+TRICK_ICG_EXCLUDE += :$(MODELS)/IcgExclude.hh
+TRICK_ICG_EXCLUDE += :$(MODELS)/icg_exclude
+TRICK_ICG_EXCLUDE += :$(MODELS)/symlinks/exclude_link_path/links/icg_exclude
+TRICK_ICG_EXCLUDE += :$(MODELS)/symlinks/exclude_real_path/real/icg_exclude
+
+TRICK_SWIG_EXCLUDE += :$(MODELS)/SwigExclude.hh
+TRICK_SWIG_EXCLUDE += :$(MODELS)/swig_exclude
+TRICK_SWIG_EXCLUDE += :$(MODELS)/symlinks/exclude_link_path/links/swig_exclude
+TRICK_SWIG_EXCLUDE += :$(MODELS)/symlinks/exclude_real_path/real/swig_exclude
+
+TRICK_EXT_LIB_DIRS += :$(MODELS)/ExtLibDir.hh
+TRICK_EXT_LIB_DIRS += :$(MODELS)/ExtLibDir.cpp
+TRICK_EXT_LIB_DIRS += :$(MODELS)/ext_lib_dir
+TRICK_EXT_LIB_DIRS += :$(MODELS)/symlinks/exclude_link_path/links/ext_lib_dir
+TRICK_EXT_LIB_DIRS += :$(MODELS)/symlinks/exclude_real_path/real/ext_lib_dir
+
+TRICKIFIED := $(MODELS)/trickified/trickified.o
+TRICK_PYTHON_PATH += :$(MODELS)/trickified/python
+TRICK_SWIG_FLAGS += -I$(MODELS)/trickified
+TRICK_LDFLAGS += $(TRICKIFIED)
+$(SWIG_SRC): $(TRICKIFIED)
+
+$(TRICKIFIED):
+	@$(MAKE) -s -C $(MODELS)/trickified
diff --git a/test/SIM_exclusion_mechanisms/models/Exclude.hh b/test/SIM_exclusion_mechanisms/models/Exclude.hh
new file mode 100644
index 00000000..b748403b
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/Exclude.hh
@@ -0,0 +1,22 @@
+#ifndef EXCLUDE1
+#define EXCLUDE1
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class Exclude1A {
+    private:
+    void operator=(const Exclude1A&);
+};
+
+class Exclude1B {
+    const std::vector<Exclude1A> foos;
+};
+
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/ExtLibDir.cpp
new file mode 100644
index 00000000..02086a78
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/ExtLibDir.cpp
@@ -0,0 +1 @@
+This file should be excluded from the build. Is is meant to cause a compiler error if Trick tries to build it.
diff --git a/test/SIM_exclusion_mechanisms/models/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/ExtLibDir.hh
new file mode 100644
index 00000000..9972b8e0
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/ExtLibDir.hh
@@ -0,0 +1,19 @@
+// @trick_parse{everything}
+// @trick_link_dependency{ExtLibDir.cpp}
+
+#ifndef EXT_LIB_DIR1
+#define EXT_LIB_DIR1
+
+/**
+ * This file is part of a Trickified library and is meant to be excluded from
+ * ICG via TRICK_EXT_LIB_DIRS. If the exclusion logic failts, the generated I/O
+ * code will result in multiple-definition errors at link time as the symbols
+ * will also exist in the Trickified partially-linked object.
+ */
+class ExtLibDir1 {
+    private:
+    void operator=(const ExtLibDir1&);
+};
+
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/Foo.cpp b/test/SIM_exclusion_mechanisms/models/Foo.cpp
new file mode 100644
index 00000000..222ffaa3
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/Foo.cpp
@@ -0,0 +1,2 @@
+// @trick_link_dependency{ExtLibDir.cpp}
+// @trick_link_dependency{ext_lib_dir/ExtLibDir.cpp}
diff --git a/test/SIM_exclusion_mechanisms/models/Foo.hh b/test/SIM_exclusion_mechanisms/models/Foo.hh
new file mode 100644
index 00000000..fa57158a
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/Foo.hh
@@ -0,0 +1,22 @@
+// @trick_parse{everything}
+// @trick_link_dependency{Foo.cpp}
+
+#include "Exclude.hh"
+#include "exclude/Exclude.hh"
+#include "symlinks/exclude_link_path/links/exclude/Exclude.hh"
+#include "symlinks/exclude_real_path/links/exclude/Exclude.hh"
+
+#include "IcgExclude.hh"
+#include "icg_exclude/IcgExclude.hh"
+#include "symlinks/exclude_link_path/links/icg_exclude/IcgExclude.hh"
+#include "symlinks/exclude_real_path/links/icg_exclude/IcgExclude.hh"
+
+#include "SwigExclude.hh"
+#include "swig_exclude/SwigExclude.hh"
+#include "symlinks/exclude_link_path/links/swig_exclude/SwigExclude.hh"
+#include "symlinks/exclude_real_path/links/swig_exclude/SwigExclude.hh"
+
+#include "ExtLibDir.hh"
+#include "ext_lib_dir/ExtLibDir.hh"
+#include "symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh"
+#include "symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh"
diff --git a/test/SIM_exclusion_mechanisms/models/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/IcgExclude.hh
new file mode 100644
index 00000000..e2e42e1d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/IcgExclude.hh
@@ -0,0 +1,18 @@
+#ifndef ICG_EXCLUDE1
+#define ICG_EXCLUDE1
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class IcgExclude1A {
+    private:
+    void operator=(const IcgExclude1A&);
+};
+
+class IcgExclude1B {
+    const std::vector<IcgExclude1A> foos;
+};
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/SwigExclude.hh
new file mode 100644
index 00000000..1c9c3a1d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/SwigExclude.hh
@@ -0,0 +1,3 @@
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/exclude/Exclude.hh b/test/SIM_exclusion_mechanisms/models/exclude/Exclude.hh
new file mode 100644
index 00000000..18fabf1a
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/exclude/Exclude.hh
@@ -0,0 +1,22 @@
+#ifndef EXCLUDE2
+#define EXCLUDE2
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class Exclude2A {
+    private:
+    void operator=(const Exclude2A&);
+};
+
+class Exclude2B {
+    const std::vector<Exclude2A> foos;
+};
+
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.cpp
new file mode 100644
index 00000000..02086a78
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.cpp
@@ -0,0 +1 @@
+This file should be excluded from the build. Is is meant to cause a compiler error if Trick tries to build it.
diff --git a/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.hh
new file mode 100644
index 00000000..dd9b4161
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/ext_lib_dir/ExtLibDir.hh
@@ -0,0 +1,19 @@
+// @trick_parse{everything}
+// @trick_link_dependency{ExtLibDir.cpp}
+
+#ifndef EXT_LIB_DIR2
+#define EXT_LIB_DIR2
+
+/**
+ * This file is part of a Trickified library and is meant to be excluded from
+ * ICG via TRICK_EXT_LIB_DIRS. If the exclusion logic failts, the generated I/O
+ * code will result in multiple-definition errors at link time as the symbols
+ * will also exist in the Trickified partially-linked object.
+ */
+class ExtLibDir2 {
+    private:
+    void operator=(const ExtLibDir2&);
+};
+
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/icg_exclude/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/icg_exclude/IcgExclude.hh
new file mode 100644
index 00000000..a8dce493
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/icg_exclude/IcgExclude.hh
@@ -0,0 +1,18 @@
+#ifndef ICG_EXCLUDE2
+#define ICG_EXCLUDE2
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class IcgExclude2A {
+    private:
+    void operator=(const IcgExclude2A&);
+};
+
+class IcgExclude2B {
+    const std::vector<IcgExclude2A> foos;
+};
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/swig_exclude/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/swig_exclude/SwigExclude.hh
new file mode 100644
index 00000000..1c9c3a1d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/swig_exclude/SwigExclude.hh
@@ -0,0 +1,3 @@
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/exclude/Exclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/exclude/Exclude.hh
new file mode 120000
index 00000000..c7cd3b30
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/exclude/Exclude.hh
@@ -0,0 +1 @@
+../../real/exclude/Exclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.cpp
new file mode 120000
index 00000000..041627f3
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.cpp
@@ -0,0 +1 @@
+../../real/ext_lib_dir/ExtLibDir.cpp
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh
new file mode 120000
index 00000000..ab9c06eb
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh
@@ -0,0 +1 @@
+../../real/ext_lib_dir/ExtLibDir.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/icg_exclude/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/icg_exclude/IcgExclude.hh
new file mode 120000
index 00000000..24f91a3b
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/icg_exclude/IcgExclude.hh
@@ -0,0 +1 @@
+../../real/icg_exclude/IcgExclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/swig_exclude/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/swig_exclude/SwigExclude.hh
new file mode 120000
index 00000000..846ffdd0
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/links/swig_exclude/SwigExclude.hh
@@ -0,0 +1 @@
+../../real/swig_exclude/SwigExclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/exclude/Exclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/exclude/Exclude.hh
new file mode 100644
index 00000000..0082eeac
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/exclude/Exclude.hh
@@ -0,0 +1,22 @@
+#ifndef EXCLUDE5
+#define EXCLUDE5
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class Exclude5A {
+    private:
+    void operator=(const Exclude5A&);
+};
+
+class Exclude5B {
+    const std::vector<Exclude5A> foos;
+};
+
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.cpp
new file mode 100644
index 00000000..02086a78
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.cpp
@@ -0,0 +1 @@
+This file should be excluded from the build. Is is meant to cause a compiler error if Trick tries to build it.
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.hh
new file mode 100644
index 00000000..88943646
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.hh
@@ -0,0 +1,19 @@
+// @trick_parse{everything}
+// @trick_link_dependency{ExtLibDir.cpp}
+
+#ifndef EXT_LIB_DIR3
+#define EXT_LIB_DIR3
+
+/**
+ * This file is part of a Trickified library and is meant to be excluded from
+ * ICG via TRICK_EXT_LIB_DIRS. If the exclusion logic failts, the generated I/O
+ * code will result in multiple-definition errors at link time as the symbols
+ * will also exist in the Trickified partially-linked object.
+ */
+class ExtLibDir3 {
+    private:
+    void operator=(const ExtLibDir3&);
+};
+
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/icg_exclude/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/icg_exclude/IcgExclude.hh
new file mode 100644
index 00000000..82ae2979
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/icg_exclude/IcgExclude.hh
@@ -0,0 +1,18 @@
+#ifndef ICG_EXCLUDE3
+#define ICG_EXCLUDE3
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class IcgExclude3A {
+    private:
+    void operator=(const IcgExclude3A&);
+};
+
+class IcgExclude3B {
+    const std::vector<IcgExclude3A> foos;
+};
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/swig_exclude/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/swig_exclude/SwigExclude.hh
new file mode 100644
index 00000000..1c9c3a1d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_link_path/real/swig_exclude/SwigExclude.hh
@@ -0,0 +1,3 @@
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/exclude/Exclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/exclude/Exclude.hh
new file mode 120000
index 00000000..c7cd3b30
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/exclude/Exclude.hh
@@ -0,0 +1 @@
+../../real/exclude/Exclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.cpp
new file mode 120000
index 00000000..041627f3
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.cpp
@@ -0,0 +1 @@
+../../real/ext_lib_dir/ExtLibDir.cpp
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh
new file mode 120000
index 00000000..ab9c06eb
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh
@@ -0,0 +1 @@
+../../real/ext_lib_dir/ExtLibDir.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/icg_exclude/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/icg_exclude/IcgExclude.hh
new file mode 120000
index 00000000..24f91a3b
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/icg_exclude/IcgExclude.hh
@@ -0,0 +1 @@
+../../real/icg_exclude/IcgExclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/swig_exclude/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/swig_exclude/SwigExclude.hh
new file mode 120000
index 00000000..846ffdd0
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/links/swig_exclude/SwigExclude.hh
@@ -0,0 +1 @@
+../../real/swig_exclude/SwigExclude.hh
\ No newline at end of file
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/exclude/Exclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/exclude/Exclude.hh
new file mode 100644
index 00000000..30ab794e
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/exclude/Exclude.hh
@@ -0,0 +1,22 @@
+#ifndef EXCLUDE6
+#define EXCLUDE6
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class Exclude6A {
+    private:
+    void operator=(const Exclude6A&);
+};
+
+class Exclude6B {
+    const std::vector<Exclude6A> foos;
+};
+
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.cpp b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.cpp
new file mode 100644
index 00000000..02086a78
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.cpp
@@ -0,0 +1 @@
+This file should be excluded from the build. Is is meant to cause a compiler error if Trick tries to build it.
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.hh
new file mode 100644
index 00000000..4cdeb4af
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.hh
@@ -0,0 +1,19 @@
+// @trick_parse{everything}
+// @trick_link_dependency{ExtLibDir.cpp}
+
+#ifndef EXT_LIB_DIR4
+#define EXT_LIB_DIR4
+
+/**
+ * This file is part of a Trickified library and is meant to be excluded from
+ * ICG via TRICK_EXT_LIB_DIRS. If the exclusion logic failts, the generated I/O
+ * code will result in multiple-definition errors at link time as the symbols
+ * will also exist in the Trickified partially-linked object.
+ */
+class ExtLibDir4 {
+    private:
+    void operator=(const ExtLibDir4&);
+};
+
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/icg_exclude/IcgExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/icg_exclude/IcgExclude.hh
new file mode 100644
index 00000000..bda112c8
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/icg_exclude/IcgExclude.hh
@@ -0,0 +1,18 @@
+#ifndef ICG_EXCLUDE4
+#define ICG_EXCLUDE4
+
+/**
+ * This file is meant to be excluded from ICG. It will produce ICG-generated
+ * code that does not compile (as long as
+ * https://github.com/nasa/trick/issues/422 isn't fixed).
+ */
+class IcgExclude4A {
+    private:
+    void operator=(const IcgExclude4A&);
+};
+
+class IcgExclude4B {
+    const std::vector<IcgExclude4A> foos;
+};
+
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/swig_exclude/SwigExclude.hh b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/swig_exclude/SwigExclude.hh
new file mode 100644
index 00000000..1c9c3a1d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/symlinks/exclude_real_path/real/swig_exclude/SwigExclude.hh
@@ -0,0 +1,3 @@
+#ifdef SWIG
+This file is meant to be excluded from SWIG. It will cause an error if SWIG tries to process it.
+#endif
diff --git a/test/SIM_exclusion_mechanisms/models/trickified/.gitignore b/test/SIM_exclusion_mechanisms/models/trickified/.gitignore
new file mode 100644
index 00000000..11033b5d
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/trickified/.gitignore
@@ -0,0 +1,2 @@
+python
+trickified.o
diff --git a/test/SIM_exclusion_mechanisms/models/trickified/Makefile b/test/SIM_exclusion_mechanisms/models/trickified/Makefile
new file mode 100644
index 00000000..772c6ddb
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/trickified/Makefile
@@ -0,0 +1,9 @@
+SIM_HOME := $(abspath $(dir $(lastword $(MAKEFILE_LIST)))/../..)
+TRICK_HOME := $(abspath $(SIM_HOME)/../..)
+export TRICKIFY_CXX_FLAGS := -I$(SIM_HOME)/models
+
+all:
+	@$(MAKE) -s -f $(TRICK_HOME)/share/trick/makefiles/trickify.mk
+
+clean:
+	@rm -rf build python trick trickified.o
diff --git a/test/SIM_exclusion_mechanisms/models/trickified/S_source.hh b/test/SIM_exclusion_mechanisms/models/trickified/S_source.hh
new file mode 100644
index 00000000..0e71e080
--- /dev/null
+++ b/test/SIM_exclusion_mechanisms/models/trickified/S_source.hh
@@ -0,0 +1,8 @@
+#include "ExtLibDir.hh"
+#include "ext_lib_dir/ExtLibDir.hh"
+#include "symlinks/exclude_link_path/links/ext_lib_dir/ExtLibDir.hh"
+#include "symlinks/exclude_real_path/links/ext_lib_dir/ExtLibDir.hh"
+
+// https://github.com/nasa/trick/issues/881
+//#include "symlinks/exclude_link_path/real/ext_lib_dir/ExtLibDir.hh"
+//#include "symlinks/exclude_real_path/real/ext_lib_dir/ExtLibDir.hh"
diff --git a/test/makefile b/test/makefile
index 79f46a36..c2e8b138 100644
--- a/test/makefile
+++ b/test/makefile
@@ -19,6 +19,7 @@ COMPILE_DIRS = \
 SIMS_NEEDING_TEST = \
 	SIM_alloc_test \
 	SIM_demo_inputfile \
+	SIM_exclusion_mechanisms \
 	SIM_isystem \
 	SIM_measurement_units \
 	SIM_parse_s_define \
diff --git a/trick_source/codegen/Interface_Code_Gen/PrintAttributes.cpp b/trick_source/codegen/Interface_Code_Gen/PrintAttributes.cpp
index 3474d3de..bf9495fe 100644
--- a/trick_source/codegen/Interface_Code_Gen/PrintAttributes.cpp
+++ b/trick_source/codegen/Interface_Code_Gen/PrintAttributes.cpp
@@ -524,7 +524,7 @@ bool PrintAttributes::isHeaderExcluded(const std::string& header, bool exclude_e
         return true;
     }
 
-    temp = almostRealPath(header.c_str());
+    temp = realpath(header.c_str(), NULL);
     if ( temp ) {
         const std::string real_path = std::string(temp);
         free(temp) ;