diff --git a/xtest.c b/xtest.c
index 2cd8af5..3b0209e 100644
--- a/xtest.c
+++ b/xtest.c
@@ -119,7 +119,7 @@ void xtest_internal_run(xtest_test_fn fn, const char *name, xtest_param *params,
                 }
                 expecting_assertion = 0;
                 fn(fixture, current_vals);
-                int carry = 1;
+                _Bool carry = 1;
                 for (int i = num_params - 1; i >= 0; --i) {
                     validx[i] += 1;
                     if (validx[i] >= valmax[i]) {
@@ -129,7 +129,7 @@ void xtest_internal_run(xtest_test_fn fn, const char *name, xtest_param *params,
                         break;
                     }
                 }
-                if (carry == 1) break;
+                if (carry) break;
             }
         }
 
@@ -211,7 +211,7 @@ void xtest_internal_assert(const char *file, int line, const char *func, const c
 expression, invert ? "not " : "", CAST_PTR(type, expected), CAST_PTR(type, actual), file, line)
 
 void xtest_fail_assert(const char *expression, const char *file, int line, void *expected,
-                       void *actual, int invert, enum xtest_type type) {
+                       void *actual, _Bool invert, enum xtest_type type) {
     switch (type) {
         case xtest_type_bool:
             snprintf(assert_message, XTEST_ASSERT_MESSAGE_MAX_LEN, FAIL_ASSERT_FORMAT("%s"), expression,
@@ -272,15 +272,15 @@ void xtest_fail_assert(const char *expression, const char *file, int line, void
 }
 
 void
-xtest_assert_float(double expected, double actual, int precision, int invert, const char *expression, const char *file,
+xtest_assert_float(double expected, double actual, int precision, _Bool invert, const char *expression, const char *file,
                    int line) {
 
     double epsilon = 1.0;
     for (int i = 0; i < precision; ++i) epsilon /= 10.0;
     double diff = expected - actual;
     if (diff < 0) diff = -diff;
-    int equals = diff < epsilon;
-    int failed = invert == equals; // invert = true: fail if equals, invert = false: fail if not equals
+    _Bool equals = diff < epsilon;
+    _Bool failed = invert == equals; // invert = true: fail if equals, invert = false: fail if not equals
     if (!failed) return;
     snprintf(assert_message, 1024,
              "assertion failed: %s, expected %s%g but got %g (difference %g, precision %d) (%s:%d)",
@@ -294,12 +294,12 @@ size_t find_diff_offset(const char *a, const char *b, size_t length) {
     return offset;
 }
 
-void xtest_assert_mem(const char *expected, const char *actual, size_t length, int invert, const char *expression,
+void xtest_assert_mem(const char *expected, const char *actual, size_t length, _Bool invert, const char *expression,
                       const char *file,
                       int line) {
     size_t offset = find_diff_offset(expected, actual, length);
-    int equals = offset == length;
-    int failed = invert == equals; // invert = true: fail if equals, invert = false: fail if not equals
+    _Bool equals = offset == length;
+    _Bool failed = invert == equals; // invert = true: fail if equals, invert = false: fail if not equals
     if (!failed) return;
 
     if (invert) {
diff --git a/xtest.h b/xtest.h
index 1d9a2ba..5808212 100644
--- a/xtest.h
+++ b/xtest.h
@@ -44,12 +44,12 @@ enum xtest_type {
 
 
 void xtest_fail_assert(const char *expression, const char *file, int line, void *expected,
-                       void *actual, int invert, enum xtest_type type);
+                       void *actual, _Bool invert, enum xtest_type type);
 void
-xtest_assert_float(double expected, double actual, int precision, int invert, const char *expression, const char *file,
+xtest_assert_float(double expected, double actual, int precision, _Bool invert, const char *expression, const char *file,
                    int line);
 
-void xtest_assert_mem(const char *expected, const char *actual, size_t length, int invert, const char *expression, const char *file,
+void xtest_assert_mem(const char *expected, const char *actual, size_t length, _Bool invert, const char *expression, const char *file,
                       int line);
 
 void xtest_internal_run(xtest_test_fn fn, const char *name, xtest_param *params, xtest_setup_fn setup,