diff --git a/test/SIM_test_icg_file_skipped/RUN_test/unit_test.py b/test/SIM_test_icg_file_skipped/RUN_test/unit_test.py
new file mode 100644
index 00000000..20fbadac
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/RUN_test/unit_test.py
@@ -0,0 +1,2 @@
+
+trick.stop(3.0);
diff --git a/test/SIM_test_icg_file_skipped/S_define b/test/SIM_test_icg_file_skipped/S_define
new file mode 100644
index 00000000..88126cfe
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/S_define
@@ -0,0 +1,34 @@
+/************************TRICK HEADER*************************
+PURPOSE: (Test that ICG generates the correct offsets for compat15 headers even
+When they are skipped by header guard optimization. This is implemented in
+ICG's FindTrickICG class)
+LIBRARY DEPENDENCIES:
+*************************************************************/
+
+#include "sim_objects/default_trick_sys.sm"
+
+##include "Bar.hh"
+##include "Baz.hh"
+
+class TestFileSkippedSimObject : public Trick::SimObject {
+
+    public:
+
+        Bar bar;
+        Baz baz;
+
+        TestFileSkippedSimObject() {
+            ("initialization") trick_ret = bar.test_bar_member_o_correct_offset();
+            ("initialization") trick_ret = baz.test_baz_member_m_correct_offset();
+            ("default_data") trick_ret = bar.test_bar_member_o_correct_offset();
+            ("default_data") trick_ret = baz.test_baz_member_m_correct_offset();
+            (0.25, "scheduled") trick_ret = bar.test_bar_member_o_correct_offset();
+            (0.25, "scheduled") trick_ret = baz.test_baz_member_m_correct_offset();
+            ("shutdown") trick_ret = bar.test_bar_member_o_correct_offset();
+            ("shutdown") trick_ret = baz.test_baz_member_m_correct_offset();
+        }
+};
+
+TestFileSkippedSimObject testfsSimObject;
+
+
diff --git a/test/SIM_test_icg_file_skipped/S_overrides.mk b/test/SIM_test_icg_file_skipped/S_overrides.mk
new file mode 100644
index 00000000..9f0dabcb
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/S_overrides.mk
@@ -0,0 +1,4 @@
+
+TRICK_CFLAGS += -I./models
+TRICK_CXXFLAGS += -I./models
+TRICK_ICGFLAGS = "--print-TRICK-ICG=0"
diff --git a/test/SIM_test_icg_file_skipped/models/Bar.hh b/test/SIM_test_icg_file_skipped/models/Bar.hh
new file mode 100644
index 00000000..7d3ec27a
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/models/Bar.hh
@@ -0,0 +1,22 @@
+// @trick_parse{everything}
+#include "Foo.hh"
+#include "trick/memorymanager_c_intf.h"
+
+class Bar {
+    public:
+    Foo foo;
+    int o;
+
+    Bar():o(777){}
+
+    int test_bar_member_o_correct_offset() {
+        char ref_name[] = "testfsSimObject.bar.o";
+        REF2* ref = ref_attributes(ref_name);
+        if(*((int*)ref->address) == o) {
+            return 0;
+        }
+        else {
+            return 1;
+        }
+    }
+};
diff --git a/test/SIM_test_icg_file_skipped/models/Baz.hh b/test/SIM_test_icg_file_skipped/models/Baz.hh
new file mode 100644
index 00000000..f77b24d1
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/models/Baz.hh
@@ -0,0 +1,22 @@
+// @trick_parse{everything}
+#include "Foo.hh"
+#include "trick/memorymanager_c_intf.h"
+
+class Baz {
+    public:
+    Foo foo;
+    int m;
+
+    Baz(): m(42) {}
+
+    int test_baz_member_m_correct_offset() {
+        char ref_name[] = "testfsSimObject.baz.m";
+        REF2* ref = ref_attributes(ref_name);
+        if(*((int*)ref->address) == m) {
+            return 0;
+        }
+        else {
+            return 1;
+        }
+    }
+};
diff --git a/test/SIM_test_icg_file_skipped/models/Foo.hh b/test/SIM_test_icg_file_skipped/models/Foo.hh
new file mode 100644
index 00000000..f8e1c808
--- /dev/null
+++ b/test/SIM_test_icg_file_skipped/models/Foo.hh
@@ -0,0 +1,15 @@
+// @trick_parse{everything}
+#ifndef FOO_HH
+#define FOO_HH
+
+class Foo {
+public:
+    #ifndef TRICK_ICG
+    int i;
+    int j;
+    int k;
+    Foo() : i(1), j(2), k(3) {}
+    #endif
+};
+
+#endif
diff --git a/test/makefile b/test/makefile
index 36fb2b0c..6556eeb5 100644
--- a/test/makefile
+++ b/test/makefile
@@ -26,6 +26,7 @@ SIMS_TO_COMPILE_AND_RUN = \
 	SIM_stls \
 	SIM_test_dp \
 	SIM_test_dr \
+	SIM_test_icg_file_skipped \
 	SIM_test_io \
 	SIM_test_ip \
 	SIM_test_sched \
diff --git a/trick_source/codegen/Interface_Code_Gen/FindTrickICG.cpp b/trick_source/codegen/Interface_Code_Gen/FindTrickICG.cpp
index d081518c..eab21e2a 100644
--- a/trick_source/codegen/Interface_Code_Gen/FindTrickICG.cpp
+++ b/trick_source/codegen/Interface_Code_Gen/FindTrickICG.cpp
@@ -35,6 +35,38 @@ void FindTrickICG::FileChanged(clang::SourceLocation Loc, FileChangeReason Reaso
     }
 }
 
+#if (LIBCLANG_MAJOR < 10) // TODO delete when RHEL 7 no longer supported
+void FindTrickICG::FileSkipped(const clang::FileEntry &SkippedFile,
+                           const clang::Token &FilenameTok,
+                           clang::SrcMgr::CharacteristicKind FileType) {
+    std::string file_name = SkippedFile.getName() ;
+#else
+void FindTrickICG::FileSkipped(const clang::FileEntryRef & SkippedFile, const clang::Token & FilenameTok,
+                        clang::SrcMgr::CharacteristicKind FileType) {
+    /* Files that have header guards are only preprocessed once because of an optimization.
+    We still need to add its include chain to compat15 if TRICK_ICG was found when it was
+    originally preprocessed */
+    std::string file_name = SkippedFile.getName().str() ;
+#endif
+    std::string file_path;
+    {
+        char* path_cstr = almostRealPath(file_name.c_str());
+        if(path_cstr != NULL) {
+            file_path = std::string(path_cstr);
+            free(path_cstr);
+        }
+    }
+
+    // Check if skipped header is in Compat15
+    if(hsd.isPathInCompat15(file_path)) {
+        // for each header in the stack, mark them as being exposed to TRICK_ICG
+        for (std::string& file : included_files) {
+            hsd.addTrickICGFoundFile(file);
+        }
+    }
+}
+
+
 #if (LIBCLANG_MAJOR > 3) || ((LIBCLANG_MAJOR == 3) && (LIBCLANG_MINOR >= 5))
 void FindTrickICG::If(clang::SourceLocation Loc, clang::SourceRange ConditionRange, clang::PPCallbacks::ConditionValueKind ConditionValue)
 #else
diff --git a/trick_source/codegen/Interface_Code_Gen/FindTrickICG.hh b/trick_source/codegen/Interface_Code_Gen/FindTrickICG.hh
index 157fa7a7..02160d60 100644
--- a/trick_source/codegen/Interface_Code_Gen/FindTrickICG.hh
+++ b/trick_source/codegen/Interface_Code_Gen/FindTrickICG.hh
@@ -20,6 +20,17 @@ class FindTrickICG : public clang::PPCallbacks {
                            clang::SrcMgr::CharacteristicKind FileType,
                            clang::FileID PrevFID = clang::FileID()) ;
 
+#if (LIBCLANG_MAJOR < 10) // TODO delete when RHEL 7 no longer supported
+  virtual void FileSkipped(const clang::FileEntry &SkippedFile,
+                           const clang::Token &FilenameTok,
+                           clang::SrcMgr::CharacteristicKind FileType) ;
+#else
+    // called when a header file is skipped because of a header guard optimization.
+    virtual void FileSkipped(const clang::FileEntryRef & SkippedFile,
+                        const clang::Token & FilenameTok,
+                        clang::SrcMgr::CharacteristicKind FileType) ;
+#endif
+
     // callbacks called when the preprocessor directives of types are processed.
 #if (LIBCLANG_MAJOR > 3) || ((LIBCLANG_MAJOR == 3) && (LIBCLANG_MINOR >= 5))
     virtual void If(clang::SourceLocation Loc, clang::SourceRange ConditionRange, clang::PPCallbacks::ConditionValueKind ConditionValue) ;