diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 084da59..34d6494 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -16,7 +16,7 @@
 endif()
 
 # Enable definition of various functions used throughout the testsuite
-# (hostname, strdup, fileno...) even when compiling with -std=c99. Harmless
+# (gethostname, strdup, fileno...) even when compiling with -std=c99. Harmless
 # on non-POSIX platforms.
 add_definitions("-D_POSIX_C_SOURCE=200809L")
 
diff --git a/tests/Makefile b/tests/Makefile
index d65cd93..37e8cbc 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -12,6 +12,11 @@
 		-lmbedx509$(SHARED_SUFFIX)	\
 		-lmbedcrypto$(SHARED_SUFFIX)
 
+# Enable definition of various functions used throughout the testsuite
+# (gethostname, strdup, fileno...) even when compiling with -std=c99. Harmless
+# on non-POSIX platforms.
+LOCAL_CFLAGS += -D_POSIX_C_SOURCE=200809L
+
 ifndef SHARED
 DEP=../library/libmbedcrypto.a ../library/libmbedx509.a ../library/libmbedtls.a
 else