diff --git a/src/common/include/utils.h b/src/common/include/utils.h
index 585e6c3..0e4603f 100644
--- a/src/common/include/utils.h
+++ b/src/common/include/utils.h
@@ -1,5 +1,6 @@
-#include <stdio.h>
 #include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
 
 #ifdef USE_CUDA
    #ifndef __CUDACC__
@@ -47,7 +48,7 @@ __host__ __device__
 * lower_bound <= x < upper_bound
 * lower_bound <= y < upper_bound
 */
-int not_outside(int x, int y, int lower_bound, int upper_bound);
+bool not_outside(int x, int y, int lower_bound, int upper_bound);
 
 /*
 * Partie entière supérieure de a/b
diff --git a/src/common/utils.c b/src/common/utils.c
index da2c7f8..93b1671 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #ifdef USE_CUDA
@@ -30,7 +31,7 @@ int max(int a, int b) {
 #ifdef __CUDACC__
 __host__ __device__
 #endif
-int not_outside(int x, int y, int lower_bound, int upper_bound) {
+bool not_outside(int x, int y, int lower_bound, int upper_bound) {
     return !(x < lower_bound || y < lower_bound || x >= upper_bound || y>= upper_bound);
 }
 
diff --git a/src/common/utils.cu b/src/common/utils.cu
index da2c7f8..93b1671 100644
--- a/src/common/utils.cu
+++ b/src/common/utils.cu
@@ -1,3 +1,4 @@
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
 #ifdef USE_CUDA
@@ -30,7 +31,7 @@ int max(int a, int b) {
 #ifdef __CUDACC__
 __host__ __device__
 #endif
-int not_outside(int x, int y, int lower_bound, int upper_bound) {
+bool not_outside(int x, int y, int lower_bound, int upper_bound) {
     return !(x < lower_bound || y < lower_bound || x >= upper_bound || y>= upper_bound);
 }