diff --git a/chromium-66.0.3359.170-gcc8-alignof.patch b/chromium-66.0.3359.170-gcc8-alignof.patch
new file mode 100644
index 00000000..0c2b356d
--- /dev/null
+++ b/chromium-66.0.3359.170-gcc8-alignof.patch
@@ -0,0 +1,18 @@
+diff -up chromium-66.0.3359.170/mojo/public/c/system/macros.h.gcc8-alignof chromium-66.0.3359.170/mojo/public/c/system/macros.h
+--- chromium-66.0.3359.170/mojo/public/c/system/macros.h.gcc8-alignof	2018-05-15 14:58:46.448912634 -0400
++++ chromium-66.0.3359.170/mojo/public/c/system/macros.h	2018-05-15 14:58:52.041784613 -0400
+@@ -18,7 +18,13 @@
+ #endif
+ 
+ // Like the C++11 |alignof| operator.
+-#if __cplusplus >= 201103L
++#if defined(__GNUC__) && __GNUC__ >= 8
++// GCC 8 has changed the alignof operator to return the minimal alignment
++// required by the target ABI, instead of the preferred alignment.
++// This means that on 32-bit x86, it will return 4 instead of 8.
++// Use __alignof__ instead to avoid this.
++#define MOJO_ALIGNOF(type) __alignof__(type)
++#elif __cplusplus >= 201103L
+ #define MOJO_ALIGNOF(type) alignof(type)
+ #elif defined(__GNUC__)
+ #define MOJO_ALIGNOF(type) __alignof__(type)
diff --git a/chromium.spec b/chromium.spec
index b5926143..396593f5 100644
--- a/chromium.spec
+++ b/chromium.spec
@@ -244,6 +244,10 @@ Patch95:	chromium-65.0.3325.146-GCC-IDB-methods-String-renamed-to-GetString.patc
 Patch96:	chromium-66.0.3359.117-GCC-do-not-use-initializer-list-for-NoDestructor-of-.patch
 # https://chromium.googlesource.com/chromium/src/+/b84682f31dc99b9c90f5a04947075815697c68d9%5E%21/#F0
 Patch97:	chromium-66.0.3359.139-arm-init-fix.patch
+# GCC8 has changed the alignof operator to return the minimal alignment required by the target ABI
+# instead of the preferred alignment. This means int64_t is now 4 on i686 (instead of 8).
+# Use __alignof__ to get the value we expect (and chromium checks for).
+Patch98:	chromium-66.0.3359.170-gcc8-alignof.patch
 
 
 # Use chromium-latest.py to generate clean tarball from released build tarballs, found here:
@@ -727,6 +731,7 @@ udev.
 %patch95 -p1 -b .gcc-getstring
 %patch96 -p1 -b .flatsetfix
 %patch97 -p1 -b .arm-init-fix
+%patch98 -p1 -b .gcc8-alignof
 
 # Change shebang in all relevant files in this directory and all subdirectories
 # See `man find` for how the `-exec command {} +` syntax works
@@ -1625,6 +1630,7 @@ getent group chrome-remote-desktop >/dev/null || groupadd -r chrome-remote-deskt
 %changelog
 * Tue May 15 2018 Tom Callaway <spot@fedoraproject.org> 66.0.3359.170-2
 - only x86_64 i686 have swiftshader
+- fix gcc8 alignof issue on i686
 
 * Mon May 14 2018 Tom Callaway <spot@fedoraproject.org> 66.0.3359.170-1
 - update to 66.0.3359.170