diff --git a/c/src/tests/libtests/putenvtest/init.c b/c/src/tests/libtests/putenvtest/init.c
index 6c3aa0eaf5..eb19d4af80 100644
--- a/c/src/tests/libtests/putenvtest/init.c
+++ b/c/src/tests/libtests/putenvtest/init.c
@@ -26,6 +26,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+/* putenv is beyond ANSI so prototype it here */
+int putenv(const char *string);
+
 rtems_task Init(
   rtems_task_argument argument
 );
diff --git a/testsuites/libtests/putenvtest/init.c b/testsuites/libtests/putenvtest/init.c
index 6c3aa0eaf5..eb19d4af80 100644
--- a/testsuites/libtests/putenvtest/init.c
+++ b/testsuites/libtests/putenvtest/init.c
@@ -26,6 +26,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+/* putenv is beyond ANSI so prototype it here */
+int putenv(const char *string);
+
 rtems_task Init(
   rtems_task_argument argument
 );