diff --git a/checks.c b/checks.c
index ee96a25..11a4086 100644
--- a/checks.c
+++ b/checks.c
@@ -53,7 +53,7 @@ struct check {
 	void *data;
 	bool warn, error;
 	enum checkstatus status;
-	int inprogress;
+	bool inprogress;
 	int num_prereqs;
 	struct check **prereq;
 };
@@ -141,9 +141,9 @@ static void check_nodes_props(struct check *c, struct node *dt, struct node *nod
 		check_nodes_props(c, dt, child);
 }
 
-static int run_check(struct check *c, struct node *dt)
+static bool run_check(struct check *c, struct node *dt)
 {
-	int error = 0;
+	bool error = false;
 	int i;
 
 	assert(!c->inprogress);
@@ -151,11 +151,11 @@ static int run_check(struct check *c, struct node *dt)
 	if (c->status != UNCHECKED)
 		goto out;
 
-	c->inprogress = 1;
+	c->inprogress = true;
 
 	for (i = 0; i < c->num_prereqs; i++) {
 		struct check *prq = c->prereq[i];
-		error |= run_check(prq, dt);
+		error = error || run_check(prq, dt);
 		if (prq->status != PASSED) {
 			c->status = PREREQ;
 			check_msg(c, "Failed prerequisite '%s'",
@@ -177,9 +177,9 @@ static int run_check(struct check *c, struct node *dt)
 	TRACE(c, "\tCompleted, status %d", c->status);
 
 out:
-	c->inprogress = 0;
+	c->inprogress = false;
 	if ((c->status != PASSED) && (c->error))
-		error = 1;
+		error = true;
 	return error;
 }
 
@@ -733,7 +733,7 @@ void parse_checks_option(bool warn, bool error, const char *optarg)
 	die("Unrecognized check name \"%s\"\n", name);
 }
 
-void process_checks(int force, struct boot_info *bi)
+void process_checks(bool force, struct boot_info *bi)
 {
 	struct node *dt = bi->dt;
 	int i;
diff --git a/data.c b/data.c
index 4a40c5b..4c50b12 100644
--- a/data.c
+++ b/data.c
@@ -250,20 +250,20 @@ struct data data_add_marker(struct data d, enum markertype type, char *ref)
 	return data_append_markers(d, m);
 }
 
-int data_is_one_string(struct data d)
+bool data_is_one_string(struct data d)
 {
 	int i;
 	int len = d.len;
 
 	if (len == 0)
-		return 0;
+		return false;
 
 	for (i = 0; i < len-1; i++)
 		if (d.val[i] == '\0')
-			return 0;
+			return false;
 
 	if (d.val[len-1] != '\0')
-		return 0;
+		return false;
 
-	return 1;
+	return true;
 }
diff --git a/dtc-lexer.l b/dtc-lexer.l
index 3b41bfc..369407a 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -61,7 +61,7 @@ static int dts_version = 1;
 				BEGIN(V1); \
 
 static void push_input_file(const char *filename);
-static int pop_input_file(void);
+static bool pop_input_file(void);
 %}
 
 %%
@@ -238,13 +238,13 @@ static void push_input_file(const char *filename)
 }
 
 
-static int pop_input_file(void)
+static bool pop_input_file(void)
 {
 	if (srcfile_pop() == 0)
-		return 0;
+		return false;
 
 	yypop_buffer_state();
 	yyin = current_srcfile->f;
 
-	return 1;
+	return true;
 }
diff --git a/dtc-parser.y b/dtc-parser.y
index f412460..4864631 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -31,7 +31,7 @@ extern void print_error(char const *fmt, ...);
 extern void yyerror(char const *s);
 
 extern struct boot_info *the_boot_info;
-extern int treesource_error;
+extern bool treesource_error;
 
 static unsigned long long eval_literal(const char *s, int base, int bits);
 static unsigned char eval_char_literal(const char *s);
@@ -478,7 +478,7 @@ void print_error(char const *fmt, ...)
 	srcpos_verror(&yylloc, fmt, va);
 	va_end(va);
 
-	treesource_error = 1;
+	treesource_error = true;
 }
 
 void yyerror(char const *s) {
diff --git a/dtc.c b/dtc.c
index e3c9653..d36ccdc 100644
--- a/dtc.c
+++ b/dtc.c
@@ -109,7 +109,7 @@ int main(int argc, char *argv[])
 	const char *outform = "dts";
 	const char *outname = "-";
 	const char *depname = NULL;
-	int force = 0, sort = 0;
+	bool force = false, sort = false;
 	const char *arg;
 	int opt;
 	FILE *outf = NULL;
@@ -148,7 +148,7 @@ int main(int argc, char *argv[])
 			padsize = strtol(optarg, NULL, 0);
 			break;
 		case 'f':
-			force = 1;
+			force = true;
 			break;
 		case 'q':
 			quiet++;
@@ -174,7 +174,7 @@ int main(int argc, char *argv[])
 			break;
 
 		case 's':
-			sort = 1;
+			sort = true;
 			break;
 
 		case 'W':
diff --git a/dtc.h b/dtc.h
index 264a20c..20e4d56 100644
--- a/dtc.h
+++ b/dtc.h
@@ -118,7 +118,7 @@ struct data data_append_align(struct data d, int align);
 
 struct data data_add_marker(struct data d, enum markertype type, char *ref);
 
-int data_is_one_string(struct data d);
+bool data_is_one_string(struct data d);
 
 /* DT constraints */
 
@@ -127,13 +127,13 @@ int data_is_one_string(struct data d);
 
 /* Live trees */
 struct label {
-	int deleted;
+	bool deleted;
 	char *label;
 	struct label *next;
 };
 
 struct property {
-	int deleted;
+	bool deleted;
 	char *name;
 	struct data val;
 
@@ -143,7 +143,7 @@ struct property {
 };
 
 struct node {
-	int deleted;
+	bool deleted;
 	char *name;
 	struct property *proplist;
 	struct node *children;
@@ -248,7 +248,7 @@ void sort_tree(struct boot_info *bi);
 /* Checks */
 
 void parse_checks_option(bool warn, bool error, const char *optarg);
-void process_checks(int force, struct boot_info *bi);
+void process_checks(bool force, struct boot_info *bi);
 
 /* Flattened trees */
 
diff --git a/flattree.c b/flattree.c
index 665dad7..bd99fa2 100644
--- a/flattree.c
+++ b/flattree.c
@@ -261,7 +261,7 @@ static void flatten_tree(struct node *tree, struct emitter *emit,
 {
 	struct property *prop;
 	struct node *child;
-	int seen_name_prop = 0;
+	bool seen_name_prop = false;
 
 	if (tree->deleted)
 		return;
@@ -279,7 +279,7 @@ static void flatten_tree(struct node *tree, struct emitter *emit,
 		int nameoff;
 
 		if (streq(prop->name, "name"))
-			seen_name_prop = 1;
+			seen_name_prop = true;
 
 		nameoff = stringtable_insert(strbuf, prop->name);
 
diff --git a/srcpos.c b/srcpos.c
index c20bc53..294568b 100644
--- a/srcpos.c
+++ b/srcpos.c
@@ -159,7 +159,7 @@ void srcfile_push(const char *fname)
 	current_srcfile = srcfile;
 }
 
-int srcfile_pop(void)
+bool srcfile_pop(void)
 {
 	struct srcfile_state *srcfile = current_srcfile;
 
@@ -177,7 +177,7 @@ int srcfile_pop(void)
 	 * fix this we could either allocate all the files from a
 	 * table, or use a pool allocator. */
 
-	return current_srcfile ? 1 : 0;
+	return current_srcfile ? true : false;
 }
 
 void srcfile_add_search_path(const char *dirname)
diff --git a/srcpos.h b/srcpos.h
index 93a2712..57dfa0f 100644
--- a/srcpos.h
+++ b/srcpos.h
@@ -21,6 +21,7 @@
 #define _SRCPOS_H_
 
 #include <stdio.h>
+#include <stdbool.h>
 
 struct srcfile_state {
 	FILE *f;
@@ -55,7 +56,7 @@ extern struct srcfile_state *current_srcfile; /* = NULL */
 FILE *srcfile_relative_open(const char *fname, char **fullnamep);
 
 void srcfile_push(const char *fname);
-int srcfile_pop(void);
+bool srcfile_pop(void);
 
 /**
  * Add a new directory to the search path for input files
diff --git a/treesource.c b/treesource.c
index 33eeba5..ffebb77 100644
--- a/treesource.c
+++ b/treesource.c
@@ -26,12 +26,12 @@ extern int yyparse(void);
 extern YYLTYPE yylloc;
 
 struct boot_info *the_boot_info;
-int treesource_error;
+bool treesource_error;
 
 struct boot_info *dt_from_source(const char *fname)
 {
 	the_boot_info = NULL;
-	treesource_error = 0;
+	treesource_error = false;
 
 	srcfile_push(fname);
 	yyin = current_srcfile->f;
@@ -54,7 +54,7 @@ static void write_prefix(FILE *f, int level)
 		fputc('\t', f);
 }
 
-static int isstring(char c)
+static bool isstring(char c)
 {
 	return (isprint(c)
 		|| (c == '\0')
diff --git a/util.c b/util.c
index e87d6c1..2347af9 100644
--- a/util.c
+++ b/util.c
@@ -70,7 +70,7 @@ char *join_path(const char *path, const char *name)
 	return str;
 }
 
-int util_is_printable_string(const void *data, int len)
+bool util_is_printable_string(const void *data, int len)
 {
 	const char *s = data;
 	const char *ss, *se;
diff --git a/util.h b/util.h
index 8f40b44..ccfdf4b 100644
--- a/util.h
+++ b/util.h
@@ -2,6 +2,7 @@
 #define _UTIL_H
 
 #include <stdarg.h>
+#include <stdbool.h>
 #include <getopt.h>
 
 /*
@@ -68,7 +69,7 @@ extern char *join_path(const char *path, const char *name);
  * @param len	The string length including terminator
  * @return 1 if a valid printable string, 0 if not
  */
-int util_is_printable_string(const void *data, int len);
+bool util_is_printable_string(const void *data, int len);
 
 /*
  * Parse an escaped character starting at index i in string s.  The resulting