diff --git a/sim/igen/filter.h b/sim/igen/filter.h
index dd674dde26ae..b225731add0e 100644
--- a/sim/igen/filter.h
+++ b/sim/igen/filter.h
@@ -19,6 +19,10 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_FILTER_H
+#define IGEN_FILTER_H
+
+#include "lf.h"
 
 /* NB, an empty filter is NULL */
 typedef struct _filter filter;
@@ -68,3 +72,5 @@ const char *filter_next (const filter *set, const char *member);
 
 extern void dump_filter
   (lf *file, const char *prefix, const filter *filt, const char *suffix);
+
+#endif /* IGEN_FILTER_H */
diff --git a/sim/igen/filter_host.h b/sim/igen/filter_host.h
index 104c21063d62..b226a2111fa2 100644
--- a/sim/igen/filter_host.h
+++ b/sim/igen/filter_host.h
@@ -19,9 +19,10 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifndef _FILTER_HOST_H
-#define _FILTER_HOST_H
+#ifndef IGEN_FILTER_HOST_H
+#define IGEN_FILTER_HOST_H
 
 /* Remove directory part from filename */
 extern const char *filter_filename (const char *filename);
-#endif
+
+#endif /* IGEN_FILTER_HOST_H */
diff --git a/sim/igen/gen-engine.h b/sim/igen/gen-engine.h
index bb46bed147d9..20f341526f46 100644
--- a/sim/igen/gen-engine.h
+++ b/sim/igen/gen-engine.h
@@ -19,6 +19,9 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_ENGINE_H
+#define IGEN_GEN_ENGINE_H
+
 extern void gen_engine_h
   (lf *file, const gen_table *gen, const insn_table *isa,
    cache_entry *cache_rules);
@@ -29,3 +32,5 @@ extern void gen_engine_c
 
 extern void print_engine_run_function_header
   (lf *file, const char *processor, function_decl_type decl_type);
+
+#endif /* IGEN_GEN_ENGINE_H */
diff --git a/sim/igen/gen-icache.h b/sim/igen/gen-icache.h
index de8cdfe43071..f5298e564939 100644
--- a/sim/igen/gen-icache.h
+++ b/sim/igen/gen-icache.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_ICACHE_H
+#define IGEN_GEN_ICACHE_H
 
 /* Output code to manipulate the instruction cache: either create it
    or reference it */
@@ -79,3 +81,5 @@ extern void print_icache_struct
 
 
 /* Output a single instructions decoder */
+
+#endif /* IGEN_GEN_ICACHE_H */
diff --git a/sim/igen/gen-idecode.h b/sim/igen/gen-idecode.h
index 63ae883d2192..05a7055644a9 100644
--- a/sim/igen/gen-idecode.h
+++ b/sim/igen/gen-idecode.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_IDECODE_H
+#define IGEN_GEN_IDECODE_H
 
 void print_idecode_issue_function_header
   (lf *file,
@@ -45,3 +47,5 @@ extern void print_idecode_validate
   (lf *file,
    const insn_entry *instruction,
    const insn_opcodes *opcode_paths);
+
+#endif /* IGEN_GEN_IDECODE_H */
diff --git a/sim/igen/gen-itable.h b/sim/igen/gen-itable.h
index 37d39fe84b85..2991d18390ba 100644
--- a/sim/igen/gen-itable.h
+++ b/sim/igen/gen-itable.h
@@ -19,10 +19,13 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-
+#ifndef IGEN_GEN_ITABLE_H
+#define IGEN_GEN_ITABLE_H
 
 /* Output a table of all the instructions */
 
 extern void gen_itable_h (lf *file, const insn_table *table);
 
 extern void gen_itable_c (lf *file, const insn_table *table);
+
+#endif /* IGEN_GEN_ITABLE_H */
diff --git a/sim/igen/gen-model.h b/sim/igen/gen-model.h
index 5af5d9182625..2fdea67d4dc6 100644
--- a/sim/igen/gen-model.h
+++ b/sim/igen/gen-model.h
@@ -19,8 +19,11 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-
+#ifndef IGEN_GEN_MODEL_H
+#define IGEN_GEN_MODEL_H
 
 extern void gen_model_h (lf *file, const insn_table *isa);
 
 extern void gen_model_c (lf *file, const insn_table *isa);
+
+#endif /* IGEN_GEN_MODEL_H */
diff --git a/sim/igen/gen-semantics.h b/sim/igen/gen-semantics.h
index 115251b2287a..daf5fc8ca2f9 100644
--- a/sim/igen/gen-semantics.h
+++ b/sim/igen/gen-semantics.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_SEMANTICS_H
+#define IGEN_GEN_SEMANTICS_H
 
 /* Creates the files semantics.[hc].
 
@@ -102,3 +104,5 @@ extern void print_semantic_body
    const insn_entry *instruction,
    const opcode_bits *expanded_bits,
    const insn_opcodes *opcodes);
+
+#endif /* IGEN_GEN_SEMANTICS_H */
diff --git a/sim/igen/gen-support.h b/sim/igen/gen-support.h
index fac231ed96fe..c22a89565237 100644
--- a/sim/igen/gen-support.h
+++ b/sim/igen/gen-support.h
@@ -19,7 +19,11 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_SUPPORT_H
+#define IGEN_GEN_SUPPORT_H
 
 extern void gen_support_h (lf *file, const insn_table *table);
 
 extern void gen_support_c (lf *file, const insn_table *table);
+
+#endif /* IGEN_GEN_SUPPORT_H */
diff --git a/sim/igen/gen.h b/sim/igen/gen.h
index 53225bc84298..f6a77cf80a1a 100644
--- a/sim/igen/gen.h
+++ b/sim/igen/gen.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_GEN_H
+#define IGEN_GEN_H
 
 typedef struct _opcode_field opcode_field;
 struct _opcode_field
@@ -214,3 +216,5 @@ extern void print_sim_engine_abort (lf *file, const char *message);
 extern void print_include (lf *file, igen_module module);
 extern void print_include_inline (lf *file, igen_module module);
 extern void print_includes (lf *file);
+
+#endif /* IGEN_GEN_H */
diff --git a/sim/igen/igen.h b/sim/igen/igen.h
index eb5c755aeda6..cc3edac5a761 100644
--- a/sim/igen/igen.h
+++ b/sim/igen/igen.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_IGEN_H
+#define IGEN_IGEN_H
 
 /* code-generation options: */
 
@@ -249,3 +251,5 @@ do { \
   options.gen.icache_size = 1024; \
   options.warning = warning; \
 } while (0)
+
+#endif /* IGEN_IGEN_H */
diff --git a/sim/igen/ld-cache.h b/sim/igen/ld-cache.h
index 47bf9d60dae3..a7351cd765dd 100644
--- a/sim/igen/ld-cache.h
+++ b/sim/igen/ld-cache.h
@@ -19,7 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-
+#ifndef IGEN_LD_CACHE_H
+#define IGEN_LD_CACHE_H
 
 /* For backward compatibility only - load a standalone cache macro table */
 
@@ -64,3 +65,5 @@
 
 
 extern cache_entry *load_cache_table (const char *file_name);
+
+#endif /* IGEN_LD_CACHE_H */
diff --git a/sim/igen/ld-decode.h b/sim/igen/ld-decode.h
index 739e09e5d9e6..660f3a7ccd1a 100644
--- a/sim/igen/ld-decode.h
+++ b/sim/igen/ld-decode.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_LD_DECODE_H
+#define IGEN_LD_DECODE_H
 
 /* Instruction decode table:
 
@@ -242,3 +244,5 @@ extern int decode_table_max_word_nr (const decode_table *rule);
 
 extern void dump_decode_rule
   (lf *file, const char *prefix, const decode_table *rule, const char *suffix);
+
+#endif /* IGEN_LD_DECODE_H */
diff --git a/sim/igen/ld-insn.h b/sim/igen/ld-insn.h
index d22b855e1ce1..661cd40a0e85 100644
--- a/sim/igen/ld-insn.h
+++ b/sim/igen/ld-insn.h
@@ -19,7 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-
+#ifndef IGEN_LD_INSN_H
+#define IGEN_LD_INSN_H
 
 typedef uint64_t insn_uint;
 
@@ -705,3 +706,5 @@ void dump_cache_entries
 
 void dump_insn_table
   (lf *file, const char *prefix, const insn_table *isa, const char *suffix);
+
+#endif /* IGEN_LD_INSN_H */
diff --git a/sim/igen/lf.h b/sim/igen/lf.h
index d1e2acca5480..cea86d63db13 100644
--- a/sim/igen/lf.h
+++ b/sim/igen/lf.h
@@ -19,7 +19,11 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_LF_H
+#define IGEN_LF_H
+
 #include "ansidecl.h"
+#include "misc.h"
 
 /* LF: Line Numbered Output Stream */
 
@@ -115,3 +119,5 @@ extern int lf_print__function_type_function
   (lf *file,
    print_function * print_type,
    const char *prefix, const char *trailing_space);
+
+#endif /* IGEN_LF_H */
diff --git a/sim/igen/misc.h b/sim/igen/misc.h
index 45610558a262..04a7f720b41d 100644
--- a/sim/igen/misc.h
+++ b/sim/igen/misc.h
@@ -19,7 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-
+#ifndef IGEN_MISC_H
+#define IGEN_MISC_H
 
 /* Frustrating header junk */
 
@@ -102,3 +103,5 @@ name_map;
 extern int name2i (const char *name, const name_map * map);
 
 extern const char *i2name (const int i, const name_map * map);
+
+#endif /* IGEN_MISC_H */
diff --git a/sim/igen/table.h b/sim/igen/table.h
index e6f318b4e36a..13429707f2e2 100644
--- a/sim/igen/table.h
+++ b/sim/igen/table.h
@@ -19,6 +19,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#ifndef IGEN_TABLE_H
+#define IGEN_TABLE_H
 
 /* Read a table, line by line, from a file.
 
@@ -138,3 +140,5 @@ extern char *skip_spaces (char *chp);
 extern char *skip_to_separator (char *chp, char *separators);
 
 extern char *back_spaces (char *start, char *chp);
+
+#endif /* IGEN_TABLE_H */
