diff --git a/.github/workflows/main-auto.yml b/.github/workflows/main-auto.yml
index 4333bda8d77..085f4d7ba38 100644
--- a/.github/workflows/main-auto.yml
+++ b/.github/workflows/main-auto.yml
@@ -7,7 +7,7 @@ on:
       thread_safety:
         description: "thread-safety enable/disable"
         required: true
-        type: boolean
+        type: string
       build_mode:
         description: "release vs. debug build"
         required: true
@@ -73,7 +73,7 @@ jobs:
             --with-szlib=yes
         shell: bash
         working-directory: ${{ runner.workspace }}/build
-        if: "! (inputs.thread_safety)"
+        if: ${{ inputs.thread_safety == 'disable' }}
 
       - name: Autotools Configure (Thread-Safe)
         run: |
@@ -92,7 +92,7 @@ jobs:
             --with-szlib=yes
         shell: bash
         working-directory: ${{ runner.workspace }}/build
-        if: (inputs.thread_safety)
+        if: ${{ inputs.thread_safety == 'enable' }}
 
       # BUILD
       - name: Autotools Build
@@ -104,7 +104,7 @@ jobs:
       - name: Autotools Run Tests
         run: make check -j2
         working-directory: ${{ runner.workspace }}/build
-        if: "! (inputs.thread_safety)"
+        if: ${{ inputs.thread_safety == 'disable' }}
 
       # THREAD-SAFE
       - name: Autotools Run Thread-Safe Tests
@@ -112,7 +112,7 @@ jobs:
           cd test
           ./ttsafe
         working-directory: ${{ runner.workspace }}/build
-        if: (inputs.thread_safety)
+        if: ${{ inputs.thread_safety == 'enable' }}
 
       # INSTALL (note that this runs even when we don't run the tests)
       - name: Autotools Install