diff --git a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
index 03a2473cdb..0ffd0fbfe1 100644
--- a/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
+++ b/tools/fuzz/x86_instruction_emulator/fuzz-emul.c
@@ -6,9 +6,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
-#include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
@@ -16,6 +14,14 @@
 #include <xen/xen.h>
 
 #include "x86-emulate.h"
+/*
+ * include "x86-emulate.h" prior to <stdio.h> and <string.h>:
+ * x86-emulate.h disables use of SSE registers, while <stdio.h> and <string.h>
+ * declare functions that may be always_inline and use those registers
+ * unless they have been disabled earlier, which can fail to compile.
+ */
+#include <stdio.h>
+#include <string.h>
 #include "fuzz-emul.h"
 
 #define MSR_INDEX_MAX 16
diff --git a/tools/tests/x86_emulator/wrappers.c b/tools/tests/x86_emulator/wrappers.c
index d02013c4b1..eba7cc93c5 100644
--- a/tools/tests/x86_emulator/wrappers.c
+++ b/tools/tests/x86_emulator/wrappers.c
@@ -1,5 +1,4 @@
 #include <stdarg.h>
-#include <stdio.h>
 
 #define WRAP(x) typeof(x) emul_##x
 #include "x86-emulate.h"
diff --git a/tools/tests/x86_emulator/x86-emulate.h b/tools/tests/x86_emulator/x86-emulate.h
index b249e4673c..08dead32fd 100644
--- a/tools/tests/x86_emulator/x86-emulate.h
+++ b/tools/tests/x86_emulator/x86-emulate.h
@@ -3,10 +3,34 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
+/*
+ * Use of sse registers must be disabled prior to the definition of
+ * always_inline functions that would use them (memcpy, memset, etc),
+ * so do this as early as possible, aiming to be before any always_inline
+ * functions that are used are declared.
+ * Unfortunately, this cannot be done prior to inclusion of <stdlib.h>
+ * due to functions such as 'atof' that have SSE register return declared,
+ * so do so here, immediately after that.
+ */
+#if __GNUC__ >= 6
+# pragma GCC target("no-sse")
+#endif
+ /*
+ * Attempt detection of unwanted prior inclusion of some headers known to use
+ * always_inline with SSE registers in some library / compiler / optimization
+ * combinations.
+ */
+#ifdef _STRING_H
+# error "Must not include <string.h> before x86-emulate.h"
+#endif
 #include <string.h>
 
-#if __GNUC__ >= 6
-#pragma GCC target("no-sse")
+/* EOF is a standard macro defined in <stdio.h> so use it for detection */
+#ifdef EOF
+# error "Must not include <stdio.h> before x86-emulate.h"
+#endif
+#ifdef WRAP
+# include <stdio.h>
 #endif
 
 #include <xen/xen.h>