diff --git a/.github/workflows/coverage.yaml b/.github/workflows/pr.yaml
similarity index 77%
rename from .github/workflows/coverage.yaml
rename to .github/workflows/pr.yaml
index 9d7af8b980..ccc926718a 100644
--- a/.github/workflows/coverage.yaml
+++ b/.github/workflows/pr.yaml
@@ -1,8 +1,8 @@
-name: Coverage
-on: [push, pull_request]
+name: PR
+on: [pull_request]
 
 jobs:
-  build:
+  delete-matched-asm:
     name: Check matched assembly files are deleted
     runs-on: ubuntu-latest
     steps:
diff --git a/Jenkinsfile b/Jenkinsfile
index a6bb024017..1c391301cf 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -29,6 +29,7 @@ pipeline {
                     if (env.CHANGE_ID) {
                         def us_progress = sh(returnStdout: true, script: "python3 progress.py us --pr-comment").trim()
                         def jp_progress = sh(returnStdout: true, script: "python3 progress.py jp --pr-comment").trim()
+                        def warnings = sh(returnStdout: true, script: "./tools/warnings_count/check_new_warnings.sh --pr-message").trim()
                         def comment_id = -1
 
                         for (comment in pullRequest.comments) {
@@ -37,9 +38,9 @@ pipeline {
                             }
                         }
 
-                        def message = "${us_progress}\n${jp_progress}"
+                        def message = "${us_progress}\n${jp_progress}\n${warnings}"
 
-                        if (message != "\n") {
+                        if (message != "\n\n") {
                             if (comment_id == -1) {
                                 pullRequest.comment(message)
                             } else {
@@ -63,6 +64,9 @@ pipeline {
                 sh 'python3 progress.py jp --csv >> reports/progress_jp.csv'
                 sh 'python3 progress.py jp --shield-json > reports/progress_jp_shield.json'
 
+                sh './tools/warnings_count/update_current_warnings.sh'
+                sh 'cp tools/warnings_count/warnings.txt reports/warnings.txt'
+
                 stash includes: 'reports/*', name: 'reports'
             }
         }
@@ -80,6 +84,8 @@ pipeline {
 
                 sh 'cat reports/progress_jp.csv >> /var/www/papermar.io/html/reports/progress_jp.csv'
                 sh 'cat reports/progress_jp_shield.json > /var/www/papermar.io/html/reports/progress_jp_shield.json'
+
+                sh 'cat reports/warnings.txt > /var/www/papermar.io/html/reports/warnings.txt'
             }
         }
     }
diff --git a/tools/build/configure.py b/tools/build/configure.py
index 6a349a787b..41d7541609 100755
--- a/tools/build/configure.py
+++ b/tools/build/configure.py
@@ -41,7 +41,7 @@ def write_ninja_rules(ninja: ninja_syntax.Writer, cpp: str, cppflags: str, extra
     else:
         raise Exception(f"unsupported platform {sys.platform}")
 
-    ccache = ""
+    ccache = "ccache "
 
     try:
         subprocess.call(["ccache"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
@@ -56,7 +56,7 @@ def write_ninja_rules(ninja: ninja_syntax.Writer, cpp: str, cppflags: str, extra
     CPPFLAGS = "-w -Iver/$version/build/include -Iinclude -Isrc -Iassets/$version -D_LANGUAGE_C -D_FINALROM -DVERSION=$version " \
                 "-ffreestanding -DF3DEX_GBI_2 -D_MIPS_SZLONG=32"
 
-    cflags = f"-c -G0 -O2 -fno-common -Wuninitialized -Wmissing-braces -B {BUILD_TOOLS}/cc/gcc/ {extra_cflags}"
+    cflags = f"-c -G0 -O2 -fno-common -Wuninitialized -Wmissing-braces -Wimplicit -Wredundant-decls -Wstrict-prototypes -B {BUILD_TOOLS}/cc/gcc/ {extra_cflags}"
 
     ninja.variable("python", sys.executable)
 
diff --git a/tools/warnings_count/.gitignore b/tools/warnings_count/.gitignore
new file mode 100644
index 0000000000..2211df63dd
--- /dev/null
+++ b/tools/warnings_count/.gitignore
@@ -0,0 +1 @@
+*.txt
diff --git a/tools/warnings_count/check_new_warnings.sh b/tools/warnings_count/check_new_warnings.sh
new file mode 100755
index 0000000000..6d2c6c103e
--- /dev/null
+++ b/tools/warnings_count/check_new_warnings.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+set -e
+
+# This script can be used when you want to test locally the amount of warnings produced by your changes before doing a PR.
+
+curl -L https://papermar.io/reports/warnings.txt > tools/warnings_count/warnings.txt
+
+rm -rf ver/*/build/src
+ninja | grep warning | sort | uniq > tools/warnings_count/warnings_new.txt
+
+python3 tools/warnings_count/compare_warnings.py tools/warnings_count/warnings.txt tools/warnings_count/warnings_new.txt $@
diff --git a/tools/warnings_count/compare_warnings.py b/tools/warnings_count/compare_warnings.py
new file mode 100755
index 0000000000..789f1133ea
--- /dev/null
+++ b/tools/warnings_count/compare_warnings.py
@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+
+import argparse
+import sys
+
+
+def countFileLines(filename: str) -> int:
+    with open(filename) as f:
+        return len(f.readlines())
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('currentwarnings', help="Name of file which contains the current warnings of the repo.")
+    parser.add_argument('newwarnings', help="Name of file which contains the *new* warnings of the repo.")
+    parser.add_argument("--pr-message", action="store_true")
+    args = parser.parse_args()
+
+    currentLines = countFileLines(args.currentwarnings)
+    newLines = countFileLines(args.newwarnings)
+    if newLines > currentLines:
+        stderr = False
+        if args.pr_message:
+            delta = newLines - currentLines
+
+            if delta == 1:
+                print(f"⚠️ This PR introduces a warning:")
+            else:
+                print(f"⚠️ This PR introduces {delta} warnings:")
+
+            if delta > 100:
+                stderr = True
+                print("See log for details.")
+        else:
+            print()
+            print("There are more warnings now. Go fix them!")
+            print("\tCurrent warnings: " + str(currentLines))
+            print("\tNew warnings: " + str(newLines))
+            print()
+
+        with open(args.newwarnings) as new:
+            new = new.readlines()
+            with open(args.currentwarnings) as current:
+                current = current.readlines()
+                for newLine in new:
+                    if newLine not in current:
+                        if stderr:
+                            print(newLine.strip(), file=sys.stderr)
+                        else:
+                            print("- " + newLine.strip())
+    elif newLines < currentLines:
+        delta = currentLines - newLines
+
+        if args.pr_message:
+            print(f"✅ This PR fixes {delta} warnings!")
+        else:
+            print(f"{delta} warnings fixed.")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/warnings_count/update_current_warnings.sh b/tools/warnings_count/update_current_warnings.sh
new file mode 100755
index 0000000000..826fc078fa
--- /dev/null
+++ b/tools/warnings_count/update_current_warnings.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+set -e
+
+# This script should only be used when we need to modify the accepted amount of warnings.
+
+rm -rf ver/*/build/src
+ninja | grep warning | sort | uniq > tools/warnings_count/warnings.txt