diff --git a/include/endian.h b/include/endian.h
index 267fbf00d..1c4a21de5 100644
--- a/include/endian.h
+++ b/include/endian.h
@@ -3,9 +3,11 @@
  * endian.h - bswap decls that can't go in compiler.h
  * Copyright Peter Jones <pjones@redhat.com>
  */
-
-#ifndef ENDIAN_H_
-#define ENDIAN_H_
+#ifdef SHIM_UNIT_TEST
+#include_next <endian.h>
+#endif
+#ifndef SHIM_ENDIAN_H_
+#define SHIM_ENDIAN_H_
 
 #include <stdint.h>
 
@@ -15,5 +17,5 @@ mkbi1_(uint32_t, bswap32, uint32_t, x)
 mkbi1_(uint64_t, bswap64, uint64_t, x)
 #include "system/builtins_end_.h"
 
-#endif /* !ENDIAN_H_ */
+#endif /* !SHIM_ENDIAN_H_ */
 // vim:fenc=utf-8:tw=75:noet
diff --git a/include/test.mk b/include/test.mk
index 5d74bdc21..62cf983a0 100644
--- a/include/test.mk
+++ b/include/test.mk
@@ -21,7 +21,7 @@ CFLAGS = -O2 -ggdb -std=gnu11 \
 	 -Wno-unused \
 	 -Werror \
 	 -Werror=nonnull \
-	 -Werror=nonnull-compare \
+	 $(shell $(CC) -Werror=nonnull-compare -E -x c /dev/null >/dev/null 2>&1 && echo -Werror=nonnull-compare) \
 	 $(ARCH_DEFINES) \
 	 -DEFI_FUNCTION_WRAPPER \
 	 -DGNU_EFI_USE_MS_ABI -DPAGE_SIZE=4096 \
diff --git a/lib/string.c b/lib/string.c
index 37eabe8cc..d941cd566 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -7,7 +7,13 @@
 
 #ifdef SHIM_UNIT_TEST
 #define strlen shim_strlen
+#ifdef strcmp
+#undef strcmp
+#endif
 #define strcmp shim_strcmp
+#ifdef strncmp
+#undef strncmp
+#endif
 #define strncmp shim_strncmp
 #define strncasecmp shim_strncasecmp
 #define strcasecmp shim_strcasecmp
@@ -15,11 +21,26 @@
 #define strlen shim_strlen
 #define strnlen shim_strnlen
 #define strcpy shim_strcpy
+#ifdef strncpy
+#undef strncpy
+#endif
 #define strncpy shim_strncpy
+#ifdef strdup
+#undef strdup
+#endif
 #define strdup shim_strdup
+#ifdef strndup
+#undef strndup
+#endif
 #define strndup shim_strndup
+#ifdef stpcpy
+#undef stpcpy
+#endif
 #define stpcpy shim_stpcpy
 #define strchrnul shim_strchrnul
+#ifdef strchr
+#undef strchr
+#endif
 #define strchr shim_strchr
 #endif
 
diff --git a/test-str.c b/test-str.c
index 87605b26f..70d1637c1 100644
--- a/test-str.c
+++ b/test-str.c
@@ -6,6 +6,8 @@
 #pragma GCC diagnostic error "-Wnonnull"
 #pragma GCC diagnostic error "-Wunused-function"
 
+#pragma GCC diagnostic warning "-Wcpp"
+
 #ifndef SHIM_UNIT_TEST
 #define SHIM_UNIT_TEST
 #endif
@@ -1046,8 +1048,29 @@ test_strcat(void)
 
 	memset(s1, 0, 4096);
 	assert_equal_return(strcat(s1, s0), s1, -1, "got %p expected %p\n");
+	/* For unknown reasons, gcc 4.8.5 gives us this here:
+	 * | In file included from shim.h:64:0,
+	 * |                  from test-str.c:14:
+	 * | test-str.c: In function 'test_strcat':
+	 * | include/test.h:85:10: warning: array subscript is below array bounds [-Warray-bounds]
+	 * |     printf("%s:%d:got %lld, expected zero " fmt, __func__, \
+	 * |           ^
+	 * | include/test.h:112:10: warning: array subscript is below array bounds [-Warray-bounds]
+	 * |     printf("%s:%d:got %lld, expected < 0 " fmt, __func__, \
+	 * |           ^
+	 *
+	 * This clearly isn't a useful error message, as it doesn't tell us
+	 * /anything about the problem/, but also it isn't reported on
+	 * later compilers, and it isn't clear that there's any problem
+	 * when examining these functions.
+	 *
+	 * I don't know.
+	 */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic warning "-Warray-bounds"
 	assert_zero_return(strncmp(s1, s0, sizeof(s)-1), 0, -1, "\n");
 	assert_negative_return(memcmp(s1, s0, sizeof(s)), 0, -1, "\n");
+#pragma GCC diagnostic pop
 
 	memset(s1, 0, 4096);
 	assert_equal_return(strcat(s1, s0), s1, -1, "got %p expected %p\n");
diff --git a/test.c b/test.c
index aa0da1fdf..dc71941f1 100644
--- a/test.c
+++ b/test.c
@@ -12,6 +12,9 @@
 UINT8 in_protocol = 0;
 int debug = DEFAULT_DEBUG_PRINT_STATE;
 
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wunused-function"
+
 EFI_STATUS EFIAPI
 LogError_(const char *file, int line, const char *func, const CHAR16 *fmt, ...)
 {