diff --git a/build/premake/extern_libs4.lua b/build/premake/extern_libs4.lua
index 0c165bf649..7ec313099a 100644
--- a/build/premake/extern_libs4.lua
+++ b/build/premake/extern_libs4.lua
@@ -591,9 +591,9 @@ extern_lib_defs = {
 	},
 	spidermonkey = {
 		compile_settings = function()
-			if _OPTIONS["with-system-mozjs31"] then
+			if _OPTIONS["with-system-mozjs38"] then
 				if not _OPTIONS["android"] then
-					pkgconfig_cflags("mozjs-31")
+					pkgconfig_cflags("mozjs-38")
 				end
 			else
 				if os.is("windows") then
@@ -611,12 +611,12 @@ extern_lib_defs = {
 			end
 		end,
 		link_settings = function()
-			if _OPTIONS["with-system-mozjs31"] then
+			if _OPTIONS["with-system-mozjs38"] then
 				if _OPTIONS["android"] then
-					links { "mozjs-31" }
+					links { "mozjs-38" }
 				else
 					pkgconfig_libs("nspr")
-					pkgconfig_libs("mozjs-31")
+					pkgconfig_libs("mozjs-38")
 				end
 			else
 				if os.is("macosx") then
@@ -624,9 +624,9 @@ extern_lib_defs = {
 					links { "nspr4", "plc4", "plds4" }
 				end
 				configuration "Debug"
-					links { "mozjs31-ps-debug" }
+					links { "mozjs38-ps-debug" }
 				configuration "Release"
-					links { "mozjs31-ps-release" }
+					links { "mozjs38-ps-release" }
 				configuration { }
 				add_source_lib_paths("spidermonkey")
 			end
diff --git a/build/premake/premake4.lua b/build/premake/premake4.lua
index eadceb326d..999759a38f 100644
--- a/build/premake/premake4.lua
+++ b/build/premake/premake4.lua
@@ -7,7 +7,7 @@ newoption { trigger = "icc", description = "Use Intel C++ Compiler (Linux only;
 newoption { trigger = "jenkins-tests", description = "Configure CxxTest to use the XmlPrinter runner which produces Jenkins-compatible output" }
 newoption { trigger = "minimal-flags", description = "Only set compiler/linker flags that are really needed. Has no effect on Windows builds" }
 newoption { trigger = "outpath", description = "Location for generated project files" }
-newoption { trigger = "with-system-mozjs31", description = "Search standard paths for libmozjs31, instead of using bundled copy" }
+newoption { trigger = "with-system-mozjs38", description = "Search standard paths for libmozjs38, instead of using bundled copy" }
 newoption { trigger = "with-system-nvtt", description = "Search standard paths for nvidia-texture-tools library, instead of using bundled copy" }
 newoption { trigger = "without-audio", description = "Disable use of OpenAL/Ogg/Vorbis APIs" }
 newoption { trigger = "without-lobby", description = "Disable the use of gloox and the multiplayer lobby" }
diff --git a/build/workspaces/clean-workspaces.sh b/build/workspaces/clean-workspaces.sh
index e66c7d74f6..49e2803ac8 100755
--- a/build/workspaces/clean-workspaces.sh
+++ b/build/workspaces/clean-workspaces.sh
@@ -24,9 +24,10 @@ if [ "`uname -s`" != "Darwin" ]; then
 
   (cd ../../libraries/source/fcollada/src && rm -rf ./output)
   (cd ../../libraries/source/spidermonkey && rm -f .already-built)
-  (cd ../../libraries/source/spidermonkey && rm -rf ./mozjs31)
+  (cd ../../libraries/source/spidermonkey && rm -rf ./mozjs-38.0.0)
 # Still delete the directory of the previous SpiderMonkey version to
 # avoid wasting disk space if people clean workspaces after updating.
+  (cd ../../libraries/source/spidermonkey && rm -rf ./mozjs31)
   (cd ../../libraries/source/spidermonkey && rm -rf ./mozjs24)
   (cd ../../libraries/source/nvtt/src && rm -rf ./build)
 fi
diff --git a/build/workspaces/update-workspaces.sh b/build/workspaces/update-workspaces.sh
index 5a43d13fde..ba55be2e96 100644
--- a/build/workspaces/update-workspaces.sh
+++ b/build/workspaces/update-workspaces.sh
@@ -40,7 +40,7 @@ premake_args=""
 
 without_nvtt=false
 with_system_nvtt=false
-with_system_mozjs31=false
+with_system_mozjs38=false
 enable_atlas=true
 
 for i in "$@"
@@ -48,7 +48,7 @@ do
   case $i in
     --without-nvtt ) without_nvtt=true; premake_args="${premake_args} --without-nvtt" ;;
     --with-system-nvtt ) with_system_nvtt=true; premake_args="${premake_args} --with-system-nvtt" ;;
-    --with-system-mozjs31 ) with_system_mozjs31=true; premake_args="${premake_args} --with-system-mozjs31" ;;
+    --with-system-mozjs38 ) with_system_mozjs38=true; premake_args="${premake_args} --with-system-mozjs38" ;;
     --enable-atlas ) enable_atlas=true ;;
     --disable-atlas ) enable_atlas=false ;;
     -j* ) JOBS=$i ;;
@@ -83,7 +83,7 @@ if [ "`uname -s`" != "Darwin" ]; then
   # Build/update bundled external libraries
   (cd ../../libraries/source/fcollada/src && ${MAKE} ${JOBS}) || die "FCollada build failed"
   echo
-  if [ "$with_system_mozjs31" = "false" ]; then
+  if [ "$with_system_mozjs38" = "false" ]; then
     (cd ../../libraries/source/spidermonkey && MAKE=${MAKE} JOBS=${JOBS} ./build.sh) || die "SpiderMonkey build failed"
   fi
   echo