diff --git a/2000/primenum/README.md b/2000/primenum/README.md
index 3f8913db0..16181110a 100644
--- a/2000/primenum/README.md
+++ b/2000/primenum/README.md
@@ -10,6 +10,11 @@
 make
 ```
 
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) made this more
+portable by changing the return type of `main()` to be `int` not `void`. Thank
+you Cody for your assistance!
+
+
 ### To run:
 
 ```sh
diff --git a/2000/primenum/primenum.c b/2000/primenum/primenum.c
index ab228e996..a64a1c1b4 100644
--- a/2000/primenum/primenum.c
+++ b/2000/primenum/primenum.c
@@ -1,8 +1,8 @@
-#define BeginProgram void main(int argc, char *argv[])
+#define BeginProgram int main(int argc, char *argv[])
 #define CloseBrace }
 #define CommandLineArgument -1
 #define Declare int i,j,n,Flag=1;
-#define EndOfProgram return;
+#define EndOfProgram return 0;
 #define False 0;
 #define ForLoop ;for
 #define GetCommandLineArgument n=atoi(argv[1]);