diff --git a/web/package-lock.json b/web/package-lock.json
index e959141eb7..c2feb52479 100644
--- a/web/package-lock.json
+++ b/web/package-lock.json
@@ -34,18 +34,6 @@
         "es6-promisify": "^5.0.0"
       }
     },
-    "ansi-regex": {
-      "version": "2.1.1",
-      "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-2.1.1.tgz",
-      "integrity": "sha1-w7M6te42DYbg5ijwRorn7yfWVN8=",
-      "dev": true
-    },
-    "ansi-styles": {
-      "version": "2.2.1",
-      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-2.2.1.tgz",
-      "integrity": "sha1-tDLdM1i2NM914eRmQ2gkBTPB3b4=",
-      "dev": true
-    },
     "anymatch": {
       "version": "3.0.3",
       "resolved": "https://registry.npmjs.org/anymatch/-/anymatch-3.0.3.tgz",
@@ -272,19 +260,6 @@
         "type-detect": "^4.0.5"
       }
     },
-    "chalk": {
-      "version": "1.1.3",
-      "resolved": "https://registry.npmjs.org/chalk/-/chalk-1.1.3.tgz",
-      "integrity": "sha1-qBFcVeSnAv5NFQq9OHKCKn4J/Jg=",
-      "dev": true,
-      "requires": {
-        "ansi-styles": "^2.2.1",
-        "escape-string-regexp": "^1.0.2",
-        "has-ansi": "^2.0.0",
-        "strip-ansi": "^3.0.0",
-        "supports-color": "^2.0.0"
-      }
-    },
     "check-error": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/check-error/-/check-error-1.0.2.tgz",
@@ -335,35 +310,6 @@
         }
       }
     },
-    "clone": {
-      "version": "2.1.1",
-      "resolved": "https://registry.npmjs.org/clone/-/clone-2.1.1.tgz",
-      "integrity": "sha1-0hfR6WERjjrJpLi7oyhVU79kfNs=",
-      "dev": true
-    },
-    "clone-buffer": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/clone-buffer/-/clone-buffer-1.0.0.tgz",
-      "integrity": "sha1-4+JbIHrE5wGvch4staFnksrD3Fg=",
-      "dev": true
-    },
-    "clone-stats": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/clone-stats/-/clone-stats-1.0.0.tgz",
-      "integrity": "sha1-s3gt/4u1R04Yuba/D9/ngvh3doA=",
-      "dev": true
-    },
-    "cloneable-readable": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/cloneable-readable/-/cloneable-readable-1.0.0.tgz",
-      "integrity": "sha1-pikNQT8hemEjL5XkWP84QYz7ARc=",
-      "dev": true,
-      "requires": {
-        "inherits": "^2.0.1",
-        "process-nextick-args": "^1.0.6",
-        "through2": "^2.0.1"
-      }
-    },
     "color-convert": {
       "version": "1.9.1",
       "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-1.9.1.tgz",
@@ -439,12 +385,6 @@
       "integrity": "sha512-YNZN8lt82XIMLnLirj9MhKDFZHalwzzrL9YLt6eb0T5D0EDl4IQ90IGkua8mHbnxNrkj1d8hbdizMc0Qmg1WnQ==",
       "dev": true
     },
-    "core-util-is": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
-      "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac=",
-      "dev": true
-    },
     "css-line-break": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/css-line-break/-/css-line-break-1.0.1.tgz",
@@ -897,16 +837,11 @@
         "is-glob": "^4.0.1"
       }
     },
-    "google-closure-compiler": {
-      "version": "20171203.0.0",
-      "resolved": "https://registry.npmjs.org/google-closure-compiler/-/google-closure-compiler-20171203.0.0.tgz",
-      "integrity": "sha1-gpW5QFo145HB2I0IJYBo4x0TEaE=",
-      "dev": true,
-      "requires": {
-        "chalk": "^1.0.0",
-        "vinyl": "^2.0.1",
-        "vinyl-sourcemaps-apply": "^0.2.0"
-      }
+    "google-closure-compiler-java": {
+      "version": "20200224.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler-java/-/google-closure-compiler-java-20200224.0.0.tgz",
+      "integrity": "sha512-palFcDoScauZjWIsGDzMK6h+IctcRb55I3wJX8Ko/DTSz72xwadRdKm0lGt8OoYL7SKEO+IjgD7s8XrAGpLnlQ==",
+      "dev": true
     },
     "graceful-fs": {
       "version": "4.2.0",
@@ -929,15 +864,6 @@
         "function-bind": "^1.1.1"
       }
     },
-    "has-ansi": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/has-ansi/-/has-ansi-2.0.0.tgz",
-      "integrity": "sha1-NPUEnOHs3ysGSa8+8k5F7TVBbZE=",
-      "dev": true,
-      "requires": {
-        "ansi-regex": "^2.0.0"
-      }
-    },
     "has-binary2": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/has-binary2/-/has-binary2-1.0.3.tgz",
@@ -1154,12 +1080,6 @@
         "has-symbols": "^1.0.0"
       }
     },
-    "isarray": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
-      "integrity": "sha1-u5NdSFgsuhaMBoNJV6VKPgcSTxE=",
-      "dev": true
-    },
     "isbinaryfile": {
       "version": "3.0.3",
       "resolved": "https://registry.npmjs.org/isbinaryfile/-/isbinaryfile-3.0.3.tgz",
@@ -1803,12 +1723,6 @@
       "integrity": "sha512-oLHIdio3tZ0qH76NybpeneBhYVj0QFTfXEFTc/B3zKQspYfYYkWYgFsmzo+4kvId/bQRcNkVeguI3y+CD22BtA==",
       "dev": true
     },
-    "process-nextick-args": {
-      "version": "1.0.7",
-      "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-1.0.7.tgz",
-      "integrity": "sha1-FQ4gt1ZZCtP5EJPyWk8q2L/zC6M=",
-      "dev": true
-    },
     "ps-tree": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/ps-tree/-/ps-tree-1.1.1.tgz",
@@ -1860,21 +1774,6 @@
         "unpipe": "1.0.0"
       }
     },
-    "readable-stream": {
-      "version": "2.3.3",
-      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.3.tgz",
-      "integrity": "sha512-m+qzzcn7KUxEmd1gMbchF+Y2eIUbieUaxkWtptyHywrX0rE8QEYqPC07Vuy4Wm32/xE16NcdBctb8S0Xe/5IeQ==",
-      "dev": true,
-      "requires": {
-        "core-util-is": "~1.0.0",
-        "inherits": "~2.0.3",
-        "isarray": "~1.0.0",
-        "process-nextick-args": "~1.0.6",
-        "safe-buffer": "~5.1.1",
-        "string_decoder": "~1.0.3",
-        "util-deprecate": "~1.0.1"
-      }
-    },
     "readdirp": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/readdirp/-/readdirp-3.1.1.tgz",
@@ -1884,18 +1783,6 @@
         "picomatch": "^2.0.4"
       }
     },
-    "remove-trailing-separator": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/remove-trailing-separator/-/remove-trailing-separator-1.1.0.tgz",
-      "integrity": "sha1-wkvOKig62tW8P1jg1IJJuSN52O8=",
-      "dev": true
-    },
-    "replace-ext": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/replace-ext/-/replace-ext-1.0.0.tgz",
-      "integrity": "sha1-3mMSg3P8v3w8z6TeWkgMRaZ5WOs=",
-      "dev": true
-    },
     "require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",
@@ -2085,12 +1972,6 @@
         }
       }
     },
-    "source-map": {
-      "version": "0.5.7",
-      "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.5.7.tgz",
-      "integrity": "sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=",
-      "dev": true
-    },
     "source-map-support": {
       "version": "0.5.10",
       "resolved": "https://registry.npmjs.org/source-map-support/-/source-map-support-0.5.10.tgz",
@@ -2195,30 +2076,6 @@
         }
       }
     },
-    "string_decoder": {
-      "version": "1.0.3",
-      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.0.3.tgz",
-      "integrity": "sha512-4AH6Z5fzNNBcH+6XDMfA/BTt87skxqJlO0lAh3Dker5zThcAxG6mKz+iGu308UKoPPQ8Dcqx/4JhujzltRa+hQ==",
-      "dev": true,
-      "requires": {
-        "safe-buffer": "~5.1.0"
-      }
-    },
-    "strip-ansi": {
-      "version": "3.0.1",
-      "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-3.0.1.tgz",
-      "integrity": "sha1-ajhfuIU9lS1f8F0Oiq+UJ43GPc8=",
-      "dev": true,
-      "requires": {
-        "ansi-regex": "^2.0.0"
-      }
-    },
-    "supports-color": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-2.0.0.tgz",
-      "integrity": "sha1-U10EXOa2Nj+kARcIRimZXp3zJMc=",
-      "dev": true
-    },
     "temp-fs": {
       "version": "0.9.9",
       "resolved": "https://registry.npmjs.org/temp-fs/-/temp-fs-0.9.9.tgz",
@@ -2245,16 +2102,6 @@
       "integrity": "sha1-DdTJ/6q8NXlgsbckEV1+Doai4fU=",
       "dev": true
     },
-    "through2": {
-      "version": "2.0.3",
-      "resolved": "https://registry.npmjs.org/through2/-/through2-2.0.3.tgz",
-      "integrity": "sha1-AARWmzfHx0ujnEPzzteNGtlBQL4=",
-      "dev": true,
-      "requires": {
-        "readable-stream": "^2.1.5",
-        "xtend": "~4.0.1"
-      }
-    },
     "tmp": {
       "version": "0.0.33",
       "resolved": "https://registry.npmjs.org/tmp/-/tmp-0.0.33.tgz",
@@ -2374,41 +2221,12 @@
         }
       }
     },
-    "util-deprecate": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
-      "integrity": "sha1-RQ1Nyfpw3nMnYvvS1KKJgUGaDM8=",
-      "dev": true
-    },
     "utils-merge": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/utils-merge/-/utils-merge-1.0.1.tgz",
       "integrity": "sha1-n5VxD1CiZ5R7LMwSR0HBAoQn5xM=",
       "dev": true
     },
-    "vinyl": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/vinyl/-/vinyl-2.1.0.tgz",
-      "integrity": "sha1-Ah+cLPlR1rk5lDyJ617lrdT9kkw=",
-      "dev": true,
-      "requires": {
-        "clone": "^2.1.1",
-        "clone-buffer": "^1.0.0",
-        "clone-stats": "^1.0.0",
-        "cloneable-readable": "^1.0.0",
-        "remove-trailing-separator": "^1.0.1",
-        "replace-ext": "^1.0.0"
-      }
-    },
-    "vinyl-sourcemaps-apply": {
-      "version": "0.2.1",
-      "resolved": "https://registry.npmjs.org/vinyl-sourcemaps-apply/-/vinyl-sourcemaps-apply-0.2.1.tgz",
-      "integrity": "sha1-q2VJ1h0XLCsbh75cUI0jnI74dwU=",
-      "dev": true,
-      "requires": {
-        "source-map": "^0.5.1"
-      }
-    },
     "void-elements": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/void-elements/-/void-elements-2.0.1.tgz",
@@ -2496,12 +2314,6 @@
       "integrity": "sha1-wodrBhaKrcQOV9l+gRkayPQ5iz4=",
       "dev": true
     },
-    "xtend": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/xtend/-/xtend-4.0.1.tgz",
-      "integrity": "sha1-pcbVMr5lbiPbgg77lDofBJmNY68=",
-      "dev": true
-    },
     "y18n": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/y18n/-/y18n-4.0.0.tgz",
diff --git a/web/package.json b/web/package.json
index 46b4b04ab7..fd5964c74e 100644
--- a/web/package.json
+++ b/web/package.json
@@ -19,7 +19,7 @@
   "homepage": "https://github.com/keymanapp/keyman#readme",
   "devDependencies": {
     "chai": "^4.2.0",
-    "google-closure-compiler": "^20171203.0.0",
+    "google-closure-compiler-java": "^20200224.0.0",
     "html2canvas": "^1.0.0-alpha.12",
     "karma": "^4.2.0",
     "karma-browserstack-launcher": "^1.5.1",
diff --git a/web/source/build.sh b/web/source/build.sh
index a227710258..be792f890d 100755
--- a/web/source/build.sh
+++ b/web/source/build.sh
@@ -56,7 +56,7 @@ EMBED_TARGET=( "keyman.js" )
 PREDICTIVE_TEXT_SOURCE="../../common/predictive-text/unit_tests/in_browser/resources/models/simple-trie.js"
 PREDICTIVE_TEXT_OUTPUT="../testing/prediction-ui/simple-en-trie.js"
 
-: ${CLOSURECOMPILERPATH:=../node_modules/google-closure-compiler}
+: ${CLOSURECOMPILERPATH:=../node_modules/google-closure-compiler-java}
 : ${JAVA:=java}
 
 minifier="$CLOSURECOMPILERPATH/compiler.jar"
@@ -103,14 +103,35 @@ minify ( ) {
         wrapper="%output%"
     fi
 
+    OUTPUT="$2/$1"
+
     # --source_map_location_mapping - maps paths on INPUT source maps for consumption by Closure.
     # ../../.. => keymanapp, ../.. => keymanapp/keyman.  We have TS root sources on 'keyman'.
     $minifycmd $defines --source_map_input "$INTERMEDIATE/$1|$INTERMEDIATE/$1.map" \
-        --create_source_map $2/$1.map --source_map_include_content \
+        --create_source_map "$2/$1.map" --source_map_include_content \
         --source_map_location_mapping "$INTERMEDIATE|../../.." \
-        --js $INTERMEDIATE/$1 --compilation_level $3 \
-        --js_output_file $2/$1 --warning_level VERBOSE --output_wrapper "$wrapper
+        --js "$INTERMEDIATE/$1" --compilation_level $3 \
+        --js_output_file "$OUTPUT" --warning_level VERBOSE --output_wrapper "$wrapper
 //# sourceMappingURL=$1.map"
+
+    # Now to clean the source map.
+    OUTPUT_SOURCEMAP="$OUTPUT.map"
+    assert "$OUTPUT"
+    assert "$SOURCEMAP"
+
+    RELATIVE_ESCAPES="\.\.\/\.\.\/\.\.\/" #../../..
+    sed -i '' "s/$RELATIVE_ESCAPES//g" "$OUTPUT_SOURCEMAP"
+
+    PATH_PREFIX="\.\.\/release\/web\/"
+    sed -i '' "s/$PATH_PREFIX//g" "$OUTPUT_SOURCEMAP"
+
+    # Force our preferred source-map rooting scheme.  Does so kind of hackily, but it
+    # gets the job done.  The next best alternatives (npm install node-jq or jq.node)
+    # have age or auditing issues.
+    INSERTION_MATCH="^\"file\""
+    INSERTION_REPLACEMENT="\"sourceRoot\": \"\/keyman\/\",\"file\""
+    # Kinda hacky, but it gets the job done.
+    sed -i '' "s/$INSERTION_MATCH/$INSERTION_REPLACEMENT/g" "$OUTPUT_SOURCEMAP"
 }
 
 # $1 - target (WEB, EMBEDDED)