diff --git a/packages/angular/cli/lib/config/schema.json b/packages/angular/cli/lib/config/schema.json
index 79e84e28fb3f..18d7b4a61775 100644
--- a/packages/angular/cli/lib/config/schema.json
+++ b/packages/angular/cli/lib/config/schema.json
@@ -1062,10 +1062,12 @@
                   "type": "object",
                   "properties": {
                     "src": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     },
                     "replaceWith": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     }
                   },
                   "additionalProperties": false,
@@ -1078,10 +1080,12 @@
                   "type": "object",
                   "properties": {
                     "replace": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     },
                     "with": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     }
                   },
                   "additionalProperties": false,
@@ -1955,10 +1959,12 @@
                   "type": "object",
                   "properties": {
                     "src": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     },
                     "replaceWith": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     }
                   },
                   "additionalProperties": false,
@@ -1971,10 +1977,12 @@
                   "type": "object",
                   "properties": {
                     "replace": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     },
                     "with": {
-                      "type": "string"
+                      "type": "string",
+                      "pattern": "\\.([cm]?j|t)sx?$"
                     }
                   },
                   "additionalProperties": false,
diff --git a/packages/angular_devkit/build_angular/src/browser/schema.json b/packages/angular_devkit/build_angular/src/browser/schema.json
index 7a9d32338a52..2256b9c4e2ca 100644
--- a/packages/angular_devkit/build_angular/src/browser/schema.json
+++ b/packages/angular_devkit/build_angular/src/browser/schema.json
@@ -433,10 +433,12 @@
           "type": "object",
           "properties": {
             "src": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             },
             "replaceWith": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             }
           },
           "additionalProperties": false,
@@ -449,10 +451,12 @@
           "type": "object",
           "properties": {
             "replace": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             },
             "with": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             }
           },
           "additionalProperties": false,
diff --git a/packages/angular_devkit/build_angular/src/server/schema.json b/packages/angular_devkit/build_angular/src/server/schema.json
index 289b37810a53..93e216a3cf99 100644
--- a/packages/angular_devkit/build_angular/src/server/schema.json
+++ b/packages/angular_devkit/build_angular/src/server/schema.json
@@ -259,10 +259,12 @@
           "type": "object",
           "properties": {
             "src": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             },
             "replaceWith": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             }
           },
           "additionalProperties": false,
@@ -275,10 +277,12 @@
           "type": "object",
           "properties": {
             "replace": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             },
             "with": {
-              "type": "string"
+              "type": "string",
+              "pattern": "\\.([cm]?j|t)sx?$"
             }
           },
           "additionalProperties": false,