diff --git a/build-arm-libopus.patch b/build-arm-libopus.patch
new file mode 100644
index 0000000..1b3f31b
--- /dev/null
+++ b/build-arm-libopus.patch
@@ -0,0 +1,12 @@
+diff -up firefox-66.0/media/libopus/silk/arm/arm_silk_map.c.old firefox-66.0/media/libopus/silk/arm/arm_silk_map.c
+--- firefox-66.0/media/libopus/silk/arm/arm_silk_map.c.old	2019-03-12 21:07:35.356677522 +0100
++++ firefox-66.0/media/libopus/silk/arm/arm_silk_map.c	2019-03-12 21:07:42.937693394 +0100
+@@ -28,7 +28,7 @@ POSSIBILITY OF SUCH DAMAGE.
+ # include "config.h"
+ #endif
+ 
+-#include "main_FIX.h"
++#include "fixed/main_FIX.h"
+ #include "NSQ.h"
+ #include "SigProc_FIX.h"
+ 
diff --git a/firefox.spec b/firefox.spec
index 7234e85..b07608d 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -132,6 +132,7 @@ Patch40:        build-aarch64-skia.patch
 Patch41:        build-disable-elfhack.patch
 Patch42:        mozilla-1515641-av1-build-1.patch
 Patch43:        mozilla-1515641-av1-build-2.patch
+Patch44:        build-arm-libopus.patch
 
 # Fedora specific patches
 Patch215:        firefox-enable-addons.patch
@@ -329,6 +330,7 @@ This package contains results of tests executed during build.
 %patch3  -p1 -b .arm
 %patch42 -p1 -b .mozilla-1515641
 %patch43 -p1 -b .mozilla-1515641
+%patch44 -p1 -b .build-arm-libopus
 
 # Fedora patches
 %patch215 -p1 -b .addons