diff --git a/lib/installer.js b/lib/installer.js
index fcd82f53..4232965a 100644
--- a/lib/installer.js
+++ b/lib/installer.js
@@ -150,18 +150,32 @@ function getNightlyFileName(arch) {
     let fileExt1;
     [fileExt1, ,] = getDesiredFileExts();
     if (osPlat == 'win32') {
-        versionExt = arch == 'x64' ? '-win64' : '-win32';
+        if (arch == 'x86') {
+            versionExt = '-win32';
+        }
+        else if (arch == 'aarch64') {
+            throw new Error('Aarch64 Julia is not available on Windows');
+        }
+        else if (arch == 'x64') {
+            versionExt = '-win64';
+        }
+        else {
+            throw new Error(`Architecture ${arch} is not supported on Windows`);
+        }
     }
     else if (osPlat == 'darwin') {
         if (arch == 'x86') {
-            throw new Error('32-bit Julia is not available on macOS');
+            throw new Error('32-bit (x86) Julia is not available on macOS');
         }
         else if (arch == 'aarch64') {
             versionExt = '-macaarch64';
         }
-        else {
+        else if (arch == 'x64') {
             versionExt = '-mac64';
         }
+        else {
+            throw new Error(`Architecture ${arch} is not supported on macOS`);
+        }
     }
     else if (osPlat === 'linux') {
         if (arch == 'x86') {
@@ -170,9 +184,12 @@ function getNightlyFileName(arch) {
         else if (arch == 'aarch64') {
             versionExt = '-linux-aarch64';
         }
-        else {
+        else if (arch == 'x64') {
             versionExt = '-linux64';
         }
+        else {
+            throw new Error(`Architecture ${arch} is not supported on Linux`);
+        }
     }
     else {
         throw new Error(`Platform ${osPlat} is not supported`);
diff --git a/src/installer.ts b/src/installer.ts
index f6c040a2..1d2b68ef 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -124,22 +124,34 @@ function getNightlyFileName(arch: string): string {
     [fileExt1, , ] = getDesiredFileExts()
 
     if (osPlat == 'win32') {
-        versionExt = arch == 'x64' ? '-win64' : '-win32'
+        if (arch == 'x86') {
+            versionExt = '-win32'
+        } else if (arch == 'aarch64') {
+            throw new Error('Aarch64 Julia is not available on Windows')
+        } else if (arch == 'x64') {
+            versionExt = '-win64'
+        } else {
+            throw new Error(`Architecture ${arch} is not supported on Windows`)
+        }
     } else if (osPlat == 'darwin') {
         if (arch == 'x86') {
-            throw new Error('32-bit Julia is not available on macOS')
+            throw new Error('32-bit (x86) Julia is not available on macOS')
         } else if (arch == 'aarch64') {
             versionExt = '-macaarch64'
-        } else {
+        } else if (arch == 'x64') {
             versionExt = '-mac64'
+        } else {
+            throw new Error(`Architecture ${arch} is not supported on macOS`)
         }
     } else if (osPlat === 'linux') {
         if (arch == 'x86') {
             versionExt = '-linux32'
         } else if (arch == 'aarch64') {
             versionExt = '-linux-aarch64'
-        } else {
+        } else if (arch == 'x64') {
             versionExt = '-linux64'
+        } else {
+            throw new Error(`Architecture ${arch} is not supported on Linux`)
         }
     } else {
         throw new Error(`Platform ${osPlat} is not supported`)