diff --git a/book/samples/03_eval1.c b/book/samples/03_eval1.c
index e0848ac..43f2e05 100644
--- a/book/samples/03_eval1.c
+++ b/book/samples/03_eval1.c
@@ -5,18 +5,15 @@
 
 #define log_log(LEVEL, MESSAGE, ...)                          \
 	printf("|" LEVEL "|`" __FILE__ "`|`%s`|%i|" MESSAGE "\n", \
-	       __func__,                                          \
-	       __LINE__ __VA_OPT__(, ) __VA_ARGS__)
+	       __func__, __LINE__ __VA_OPT__(,) __VA_ARGS__)
 
 #define log_debug(MESSAGE, ...) \
-	log_log("DEBUG", MESSAGE __VA_OPT__(, ) __VA_ARGS__)
+	log_log("DEBUG", MESSAGE __VA_OPT__(,) __VA_ARGS__)
 
-#define log_debug_eval_1(VARIABLE) log_debug("%s = %i", #VARIABLE, VARIABLE)
-#define log_debug_eval_2(VARIABLE) log_debug(#VARIABLE " = %i", VARIABLE)
-#define log_debug_eval_3(FORMAT, VARIABLE) \
-	log_debug(#VARIABLE " = " FORMAT, VARIABLE)
-#define log_debug_eval_4(FLAG, VARIABLE) \
-	log_debug(#VARIABLE " = %" FLAG, VARIABLE)
+#define log_debug_eval_1(VARIABLE)         log_debug("%s = %i", #VARIABLE, VARIABLE)
+#define log_debug_eval_2(VARIABLE)         log_debug(#VARIABLE " = %i", VARIABLE)
+#define log_debug_eval_3(FORMAT, VARIABLE) log_debug(#VARIABLE " = " FORMAT, VARIABLE)
+#define log_debug_eval_4(FLAG, VARIABLE)   log_debug(#VARIABLE " = %" FLAG, VARIABLE)
 
 int main(int arg_count, char** arg_values)
 {
diff --git a/book/samples/03_vm_gnu.c b/book/samples/03_vm_gnu.c
index 81d4740..d2332c2 100644
--- a/book/samples/03_vm_gnu.c
+++ b/book/samples/03_vm_gnu.c
@@ -1,3 +1,5 @@
+#include <stdio.h> // printf
+
 #define logger(MESSAGE, ...) printf("[log] " MESSAGE "\n", ##__VA_ARGS__)
 #define TWICE(...)           __VA_ARGS__, ##__VA_ARGS__
 
diff --git a/book/samples/03_vm_portable.c b/book/samples/03_vm_portable.c
index ed4fe7a..645a552 100644
--- a/book/samples/03_vm_portable.c
+++ b/book/samples/03_vm_portable.c
@@ -1,3 +1,5 @@
+#include <stdio.h> // printf
+
 #define logger(...) printf("[log] " __VA_ARGS__)
 
 int main(int ac, char** av)